diff --git a/core/events/events_comment_move.ts b/core/events/events_comment_move.ts
index fa05de2a8..40f2a0da3 100644
--- a/core/events/events_comment_move.ts
+++ b/core/events/events_comment_move.ts
@@ -52,7 +52,7 @@ export class CommentMove extends CommentBase {
     }
 
     this.comment_ = opt_comment;
-    this.oldCoordinate_ = opt_comment.getXY();
+    this.oldCoordinate_ = opt_comment.getRelativeToSurfaceXY();
   }
 
   /**
@@ -70,7 +70,7 @@ export class CommentMove extends CommentBase {
           'The comment is undefined. Pass a comment to ' +
           'the constructor if you want to use the record functionality');
     }
-    this.newCoordinate_ = this.comment_.getXY();
+    this.newCoordinate_ = this.comment_.getRelativeToSurfaceXY();
   }
 
   /**
@@ -180,7 +180,7 @@ export class CommentMove extends CommentBase {
           'or call fromJson');
     }
     // TODO: Check if the comment is being dragged, and give up if so.
-    const current = comment.getXY();
+    const current = comment.getRelativeToSurfaceXY();
     comment.moveBy(target.x - current.x, target.y - current.y);
   }
 }
diff --git a/core/field_colour.ts b/core/field_colour.ts
index db56acf53..73843c0b6 100644
--- a/core/field_colour.ts
+++ b/core/field_colour.ts
@@ -117,17 +117,13 @@ export class FieldColour extends Field<string> {
   protected override isDirty_ = false;
 
   /** Array of colours used by this field.  If null, use the global list. */
-  // AnyDuringMigration because:  Type 'null' is not assignable to type
-  // 'string[]'.
-  private colours_: string[] = null as AnyDuringMigration;
+  private colours_: string[]|null = null;
 
   /**
    * Array of colour tooltips used by this field.  If null, use the global
    * list.
    */
-  // AnyDuringMigration because:  Type 'null' is not assignable to type
-  // 'string[]'.
-  private titles_: string[] = null as AnyDuringMigration;
+  private titles_: string[]|null = null;
 
   /**
    * Number of colour columns used by this field.  If 0, use the global
@@ -211,8 +207,7 @@ export class FieldColour extends Field<string> {
    * @param opt_newValue The input value.
    * @returns A valid colour, or null if invalid.
    */
-  protected override doClassValidation_(opt_newValue?: AnyDuringMigration):
-      string|null {
+  protected override doClassValidation_(opt_newValue?: any): string|null {
     if (typeof opt_newValue !== 'string') {
       return null;
     }
@@ -415,9 +410,7 @@ export class FieldColour extends Field<string> {
 
   /** Handle a mouse enter event. Focus the picker. */
   private onMouseEnter_() {
-    // AnyDuringMigration because:  Property 'focus' does not exist on type
-    // 'Element'.
-    (this.picker_ as AnyDuringMigration)!.focus({preventScroll: true});
+    this.picker_?.focus({preventScroll: true});
   }
 
   /**
@@ -425,9 +418,7 @@ export class FieldColour extends Field<string> {
    * the currently highlighted colour.
    */
   private onMouseLeave_() {
-    // AnyDuringMigration because:  Property 'blur' does not exist on type
-    // 'Element'.
-    (this.picker_ as AnyDuringMigration)!.blur();
+    this.picker_?.blur();
     const highlighted = this.getHighlighted_();
     if (highlighted) {
       dom.removeClass(highlighted, 'blocklyColourHighlighted');
@@ -473,11 +464,10 @@ export class FieldColour extends Field<string> {
     this.highlightedIndex_ = index;
 
     // Update accessibility roles.
-    // AnyDuringMigration because:  Argument of type 'string | null' is not
-    // assignable to parameter of type 'string | number | boolean | string[]'.
-    aria.setState(
-        this.picker_ as Element, aria.State.ACTIVEDESCENDANT,
-        cell.getAttribute('id') as AnyDuringMigration);
+    const cellId = cell.getAttribute('id');
+    if (cellId && this.picker_) {
+      aria.setState(this.picker_, aria.State.ACTIVEDESCENDANT, cellId);
+    }
   }
 
   /** Create a colour picker dropdown editor. */
diff --git a/core/field_image.ts b/core/field_image.ts
index ab0a6bb37..a265a182b 100644
--- a/core/field_image.ts
+++ b/core/field_image.ts
@@ -35,12 +35,10 @@ export class FieldImage extends Field<string> {
   private readonly imageHeight_: number;
 
   /** The function to be called when this field is clicked. */
-  private clickHandler_: ((p1: FieldImage) => AnyDuringMigration)|null = null;
+  private clickHandler_: ((p1: FieldImage) => void)|null = null;
 
   /** The rendered field's image element. */
-  // AnyDuringMigration because:  Type 'null' is not assignable to type
-  // 'SVGImageElement'.
-  private imageElement_: SVGImageElement = null as AnyDuringMigration;
+  private imageElement_: SVGImageElement|null = null;
 
   /**
    * Editable fields usually show some sort of UI indicating they are
@@ -79,7 +77,7 @@ export class FieldImage extends Field<string> {
    */
   constructor(
       src: string|Sentinel, width: string|number, height: string|number,
-      opt_alt?: string, opt_onClick?: (p1: FieldImage) => AnyDuringMigration,
+      opt_alt?: string, opt_onClick?: (p1: FieldImage) => void,
       opt_flipRtl?: boolean, opt_config?: FieldImageConfig) {
     super(Field.SKIP_SETUP);
 
@@ -164,8 +162,7 @@ export class FieldImage extends Field<string> {
    * @param opt_newValue The input value.
    * @returns A string, or null if invalid.
    */
-  protected override doClassValidation_(opt_newValue?: AnyDuringMigration):
-      string|null {
+  protected override doClassValidation_(opt_newValue?: any): string|null {
     if (typeof opt_newValue !== 'string') {
       return null;
     }
@@ -226,7 +223,7 @@ export class FieldImage extends Field<string> {
    * @param func The function that is called when the image is clicked, or null
    *     to remove.
    */
-  setOnClickHandler(func: ((p1: FieldImage) => AnyDuringMigration)|null) {
+  setOnClickHandler(func: ((p1: FieldImage) => void)|null) {
     this.clickHandler_ = func;
   }
 
diff --git a/core/interfaces/i_copyable.ts b/core/interfaces/i_copyable.ts
index 9c780a317..4c6a7a62c 100644
--- a/core/interfaces/i_copyable.ts
+++ b/core/interfaces/i_copyable.ts
@@ -31,7 +31,7 @@ export namespace ICopyable {
   export interface CopyData {
     saveInfo: Object|Element;
     source: WorkspaceSvg;
-    typeCounts: Object|null;
+    typeCounts: {[key: string]: number}|null;
   }
 }
 
diff --git a/core/interfaces/i_selectable_toolbox_item.ts b/core/interfaces/i_selectable_toolbox_item.ts
index e7fe06f86..765a42c6e 100644
--- a/core/interfaces/i_selectable_toolbox_item.ts
+++ b/core/interfaces/i_selectable_toolbox_item.ts
@@ -61,3 +61,11 @@ export interface ISelectableToolboxItem extends IToolboxItem {
    */
   onClick(_e: Event): void;
 }
+
+/**
+ * Type guard that checks whether an IToolboxItem is an ISelectableToolboxItem.
+ */
+export function isSelectableToolboxItem(toolboxItem: IToolboxItem):
+    toolboxItem is ISelectableToolboxItem {
+  return toolboxItem.isSelectable();
+}
diff --git a/core/toolbox/collapsible_category.ts b/core/toolbox/collapsible_category.ts
index 1c6ff27fd..c6f45ebdd 100644
--- a/core/toolbox/collapsible_category.ts
+++ b/core/toolbox/collapsible_category.ts
@@ -42,8 +42,6 @@ export class CollapsibleToolboxCategory extends ToolboxCategory implements
 
   /** The child toolbox items for this category. */
   protected toolboxItems_: IToolboxItem[] = [];
-  override flyoutItems_: AnyDuringMigration;
-  override isHidden_: AnyDuringMigration;
 
   /**
    * @param categoryDef The information needed to create a category in the
@@ -60,25 +58,18 @@ export class CollapsibleToolboxCategory extends ToolboxCategory implements
 
   override makeDefaultCssConfig_() {
     const cssConfig = super.makeDefaultCssConfig_();
-    (cssConfig as AnyDuringMigration)['contents'] = 'blocklyToolboxContents';
+    cssConfig['contents'] = 'blocklyToolboxContents';
     return cssConfig;
   }
 
   override parseContents_(categoryDef: toolbox.CategoryInfo) {
-    // AnyDuringMigration because:  Element implicitly has an 'any' type because
-    // expression of type '"contents"' can't be used to index type
-    // 'CategoryInfo'.
-    const contents = (categoryDef as AnyDuringMigration)['contents'];
-    let prevIsFlyoutItem = true;
-
-    // AnyDuringMigration because:  Element implicitly has an 'any' type because
-    // expression of type '"custom"' can't be used to index type 'CategoryInfo'.
-    if ((categoryDef as AnyDuringMigration)['custom']) {
-      // AnyDuringMigration because:  Element implicitly has an 'any' type
-      // because expression of type '"custom"' can't be used to index type
-      // 'CategoryInfo'.
-      this.flyoutItems_ = (categoryDef as AnyDuringMigration)['custom'];
-    } else if (contents) {
+    if ('custom' in categoryDef) {
+      this.flyoutItems_ = categoryDef['custom'];
+    } else {
+      const contents = categoryDef['contents'];
+      if (!contents) return;
+      this.flyoutItems_ = [];
+      let prevIsFlyoutItem = true;
       for (let i = 0; i < contents.length; i++) {
         const itemDef = contents[i];
         // Separators can exist as either a flyout item or a toolbox item so
@@ -123,8 +114,8 @@ export class CollapsibleToolboxCategory extends ToolboxCategory implements
     super.init();
 
     this.setExpanded(
-        (this.toolboxItemDef_ as AnyDuringMigration)['expanded'] === 'true' ||
-        (this.toolboxItemDef_ as AnyDuringMigration)['expanded']);
+        this.toolboxItemDef_['expanded'] === 'true' ||
+        !!this.toolboxItemDef_['expanded']);
   }
 
   override createDom_() {
@@ -141,7 +132,7 @@ export class CollapsibleToolboxCategory extends ToolboxCategory implements
   override createIconDom_() {
     const toolboxIcon = document.createElement('span');
     if (!this.parentToolbox_.isHorizontal()) {
-      const className = (this.cssConfig_ as AnyDuringMigration)['icon'];
+      const className = this.cssConfig_['icon'];
       if (className) {
         dom.addClass(toolboxIcon, className);
       }
@@ -161,7 +152,7 @@ export class CollapsibleToolboxCategory extends ToolboxCategory implements
   protected createSubCategoriesDom_(subcategories: IToolboxItem[]):
       HTMLDivElement {
     const contentsContainer = document.createElement('div');
-    const className = (this.cssConfig_ as AnyDuringMigration)['contents'];
+    const className = this.cssConfig_['contents'];
     if (className) {
       dom.addClass(contentsContainer, className);
     }
diff --git a/core/toolbox/toolbox.ts b/core/toolbox/toolbox.ts
index 9b700fcf7..8c1aeb577 100644
--- a/core/toolbox/toolbox.ts
+++ b/core/toolbox/toolbox.ts
@@ -29,6 +29,7 @@ import type {IDraggable} from '../interfaces/i_draggable.js';
 import type {IFlyout} from '../interfaces/i_flyout.js';
 import type {IKeyboardAccessible} from '../interfaces/i_keyboard_accessible.js';
 import type {ISelectableToolboxItem} from '../interfaces/i_selectable_toolbox_item.js';
+import {isSelectableToolboxItem} from '../interfaces/i_selectable_toolbox_item.js';
 import type {IStyleable} from '../interfaces/i_styleable.js';
 import type {IToolbox} from '../interfaces/i_toolbox.js';
 import type {IToolboxItem} from '../interfaces/i_toolbox_item.js';
@@ -100,7 +101,6 @@ export class Toolbox extends DeleteArea implements IAutoHideable,
    * Ex: [[node, name, func], [node, name, func]].
    */
   protected boundEvents_: browserEvents.Data[] = [];
-  override wouldDelete_: AnyDuringMigration;
 
   /** The workspace this toolbox is on. */
   protected readonly workspace_: WorkspaceSvg;
@@ -112,10 +112,9 @@ export class Toolbox extends DeleteArea implements IAutoHideable,
     this.workspace_ = workspace;
 
     /** The JSON describing the contents of this toolbox. */
-    // AnyDuringMigration because:  Type 'ToolboxInfo | { contents: never[]; }'
-    // is not assignable to type 'ToolboxInfo'.
-    this.toolboxDef_ = (workspace.options.languageTree || {'contents': []}) as
-        AnyDuringMigration;
+    this.toolboxDef_ =
+        (workspace.options.languageTree ||
+         {contents: new Array<toolbox.ToolboxItemInfo>()});
 
     /** Whether the toolbox should be laid out horizontally. */
     this.horizontalLayout_ = workspace.options.horizontalLayout;
@@ -299,9 +298,8 @@ export class Toolbox extends DeleteArea implements IAutoHideable,
     if (!handled && this.selectedItem_) {
       // TODO(#6097): Figure out who implements onKeyDown and which interface it
       // should be part of.
-      const untypedItem = this.selectedItem_ as AnyDuringMigration;
-      if (untypedItem.onKeyDown) {
-        handled = untypedItem.onKeyDown(e);
+      if ((this.selectedItem_ as any).onKeyDown) {
+        handled = (this.selectedItem_ as any).onKeyDown(e);
       }
     }
 
@@ -796,33 +794,20 @@ export class Toolbox extends DeleteArea implements IAutoHideable,
   setSelectedItem(newItem: IToolboxItem|null) {
     const oldItem = this.selectedItem_;
 
-    if (!newItem && !oldItem || newItem && !newItem.isSelectable()) {
+    if (!newItem && !oldItem || newItem && !isSelectableToolboxItem(newItem)) {
       return;
     }
-    newItem = newItem as ISelectableToolboxItem;
 
-    // AnyDuringMigration because:  Argument of type 'IToolboxItem' is not
-    // assignable to parameter of type 'ISelectableToolboxItem'.
-    if (this.shouldDeselectItem_(oldItem, newItem as AnyDuringMigration) &&
-        oldItem !== null) {
+    if (this.shouldDeselectItem_(oldItem, newItem) && oldItem !== null) {
       this.deselectItem_(oldItem);
     }
 
-    // AnyDuringMigration because:  Argument of type 'IToolboxItem' is not
-    // assignable to parameter of type 'ISelectableToolboxItem'.
-    if (this.shouldSelectItem_(oldItem, newItem as AnyDuringMigration) &&
-        newItem !== null) {
-      // AnyDuringMigration because:  Argument of type 'IToolboxItem' is not
-      // assignable to parameter of type 'ISelectableToolboxItem'.
-      this.selectItem_(oldItem, newItem as AnyDuringMigration);
+    if (this.shouldSelectItem_(oldItem, newItem) && newItem !== null) {
+      this.selectItem_(oldItem, newItem);
     }
 
-    // AnyDuringMigration because:  Argument of type 'IToolboxItem' is not
-    // assignable to parameter of type 'ISelectableToolboxItem'.
-    this.updateFlyout_(oldItem, newItem as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'IToolboxItem' is not
-    // assignable to parameter of type 'ISelectableToolboxItem'.
-    this.fireSelectEvent_(oldItem, newItem as AnyDuringMigration);
+    this.updateFlyout_(oldItem, newItem);
+    this.fireSelectEvent_(oldItem, newItem);
   }
 
   /**
@@ -1044,11 +1029,10 @@ export class Toolbox extends DeleteArea implements IAutoHideable,
     this.boundEvents_ = [];
     this.contents_ = [];
 
-    // AnyDuringMigration because:  Argument of type 'HTMLDivElement | null' is
-    // not assignable to parameter of type 'Element'.
-    this.workspace_.getThemeManager().unsubscribe(
-        this.HtmlDiv as AnyDuringMigration);
-    dom.removeNode(this.HtmlDiv);
+    if (this.HtmlDiv) {
+      this.workspace_.getThemeManager().unsubscribe(this.HtmlDiv);
+      dom.removeNode(this.HtmlDiv);
+    }
   }
 }
 
diff --git a/core/utils/toolbox.ts b/core/utils/toolbox.ts
index 89b2fdbb2..28a64b778 100644
--- a/core/utils/toolbox.ts
+++ b/core/utils/toolbox.ts
@@ -99,6 +99,7 @@ export interface StaticCategoryInfo {
   colour: string|undefined;
   cssconfig: CategoryCssConfig|undefined;
   hidden: string|undefined;
+  expanded?: string|boolean;
 }
 
 /**
@@ -114,6 +115,7 @@ export interface DynamicCategoryInfo {
   colour: string|undefined;
   cssconfig: CategoryCssConfig|undefined;
   hidden: string|undefined;
+  expanded?: string|boolean;
 }
 
 /**
diff --git a/core/workspace.ts b/core/workspace.ts
index 4db632f96..4018cef9f 100644
--- a/core/workspace.ts
+++ b/core/workspace.ts
@@ -172,22 +172,11 @@ export class Workspace implements IASTNodeLocation {
    */
   private sortObjects_(a: Block|WorkspaceComment, b: Block|WorkspaceComment):
       number {
-    // AnyDuringMigration because:  Property 'getRelativeToSurfaceXY' does not
-    // exist on type 'Block | WorkspaceComment'.
-    const aXY = (a as AnyDuringMigration).getRelativeToSurfaceXY();
-    // AnyDuringMigration because:  Property 'getRelativeToSurfaceXY' does not
-    // exist on type 'Block | WorkspaceComment'.
-    const bXY = (b as AnyDuringMigration).getRelativeToSurfaceXY();
-    // AnyDuringMigration because:  Property 'offset' does not exist on type
-    // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) => number'.
-    // AnyDuringMigration because:  Property 'offset' does not exist on type
-    // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) => number'.
-    return aXY.y +
-        (Workspace.prototype.sortObjects_ as AnyDuringMigration).offset *
-        aXY.x -
-        (bXY.y +
-         (Workspace.prototype.sortObjects_ as AnyDuringMigration).offset *
-             bXY.x);
+    const offset =
+        Math.sin(math.toRadians(Workspace.SCAN_ANGLE)) * (this.RTL ? -1 : 1);
+    const aXY = a.getRelativeToSurfaceXY();
+    const bXY = b.getRelativeToSurfaceXY();
+    return aXY.y + offset * aXY.x - (bXY.y + offset * bXY.x);
   }
 
   /**
@@ -221,17 +210,7 @@ export class Workspace implements IASTNodeLocation {
     // Copy the topBlocks list.
     const blocks = (new Array<Block>()).concat(this.topBlocks);
     if (ordered && blocks.length > 1) {
-      // AnyDuringMigration because:  Property 'offset' does not exist on type
-      // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) => number'.
-      (this.sortObjects_ as AnyDuringMigration).offset =
-          Math.sin(math.toRadians(Workspace.SCAN_ANGLE));
-      if (this.RTL) {
-        // AnyDuringMigration because:  Property 'offset' does not exist on type
-        // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) =>
-        // number'.
-        (this.sortObjects_ as AnyDuringMigration).offset *= -1;
-      }
-      blocks.sort(this.sortObjects_);
+      blocks.sort(this.sortObjects_.bind(this));
     }
     return blocks;
   }
@@ -274,20 +253,10 @@ export class Workspace implements IASTNodeLocation {
     }
     const blocks = this.typedBlocksDB.get(type)!.slice(0);
     if (ordered && blocks && blocks.length > 1) {
-      // AnyDuringMigration because:  Property 'offset' does not exist on type
-      // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) => number'.
-      (this.sortObjects_ as AnyDuringMigration).offset =
-          Math.sin(math.toRadians(Workspace.SCAN_ANGLE));
-      if (this.RTL) {
-        // AnyDuringMigration because:  Property 'offset' does not exist on type
-        // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) =>
-        // number'.
-        (this.sortObjects_ as AnyDuringMigration).offset *= -1;
-      }
-      blocks.sort(this.sortObjects_);
+      blocks.sort(this.sortObjects_.bind(this));
     }
 
-    return blocks.filter(function(block: AnyDuringMigration) {
+    return blocks.filter(function(block: Block) {
       return !block.isInsertionMarker();
     });
   }
@@ -340,17 +309,7 @@ export class Workspace implements IASTNodeLocation {
     // Copy the topComments list.
     const comments = (new Array<WorkspaceComment>()).concat(this.topComments);
     if (ordered && comments.length > 1) {
-      // AnyDuringMigration because:  Property 'offset' does not exist on type
-      // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) => number'.
-      (this.sortObjects_ as AnyDuringMigration).offset =
-          Math.sin(math.toRadians(Workspace.SCAN_ANGLE));
-      if (this.RTL) {
-        // AnyDuringMigration because:  Property 'offset' does not exist on type
-        // '(a: Block | WorkspaceComment, b: Block | WorkspaceComment) =>
-        // number'.
-        (this.sortObjects_ as AnyDuringMigration).offset *= -1;
-      }
-      comments.sort(this.sortObjects_);
+      comments.sort(this.sortObjects_.bind(this));
     }
     return comments;
   }
@@ -363,7 +322,7 @@ export class Workspace implements IASTNodeLocation {
    * @returns Array of blocks.
    */
   getAllBlocks(ordered: boolean): Block[] {
-    let blocks: AnyDuringMigration[];
+    let blocks: Block[];
     if (ordered) {
       // Slow, but ordered.
       const topBlocks = this.getTopBlocks(true);
@@ -598,7 +557,7 @@ export class Workspace implements IASTNodeLocation {
    *     to be created).
    * @returns True if there is capacity for the given map, false otherwise.
    */
-  isCapacityAvailable(typeCountsMap: AnyDuringMigration): boolean {
+  isCapacityAvailable(typeCountsMap: {[key: string]: number}): boolean {
     if (!this.hasBlockLimits()) {
       return true;
     }
@@ -661,9 +620,9 @@ export class Workspace implements IASTNodeLocation {
     // Do another undo/redo if the next one is of the same group.
     while (inputStack.length && inputEvent.group &&
            inputEvent.group === inputStack[inputStack.length - 1].group) {
-      // AnyDuringMigration because:  Argument of type 'Abstract | undefined' is
-      // not assignable to parameter of type 'Abstract'.
-      events.push(inputStack.pop() as AnyDuringMigration);
+      const event = inputStack.pop();
+      if (!event) continue;
+      events.push(event);
     }
     // Push these popped events on the opposite stack.
     for (let i = 0; i < events.length; i++) {
diff --git a/core/workspace_comment.ts b/core/workspace_comment.ts
index 6e218c858..8870c6245 100644
--- a/core/workspace_comment.ts
+++ b/core/workspace_comment.ts
@@ -154,7 +154,7 @@ export class WorkspaceComment {
    *   This is not valid if the comment is currently being dragged.
    * @internal
    */
-  getXY(): Coordinate {
+  getRelativeToSurfaceXY(): Coordinate {
     return new Coordinate(this.xy_.x, this.xy_.y);
   }
 
diff --git a/core/workspace_comment_svg.ts b/core/workspace_comment_svg.ts
index 329d37ceb..4a86e89f9 100644
--- a/core/workspace_comment_svg.ts
+++ b/core/workspace_comment_svg.ts
@@ -88,7 +88,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
   private autoLayout_ = false;
   // Create core elements for the block.
   private readonly svgGroup_: SVGElement;
-  svgRect_: AnyDuringMigration;
+  svgRect_: SVGRectElement;
 
   /** Whether the comment is rendered onscreen and is a part of the DOM. */
   private rendered_ = false;
@@ -296,20 +296,18 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
    * @returns Object with .x and .y properties in workspace coordinates.
    * @internal
    */
-  getRelativeToSurfaceXY(): Coordinate {
+  override getRelativeToSurfaceXY(): Coordinate {
     let x = 0;
     let y = 0;
 
-    let element = this.getSvgRoot();
+    let element: Node|null = this.getSvgRoot();
     if (element) {
       do {
         // Loop through this comment and every parent.
         const xy = svgMath.getRelativeXY(element as Element);
         x += xy.x;
         y += xy.y;
-        // AnyDuringMigration because:  Type 'ParentNode | null' is not
-        // assignable to type 'SVGElement'.
-        element = element.parentNode as AnyDuringMigration;
+        element = element.parentNode;
       } while (element && element !== this.workspace.getBubbleCanvas() &&
                element !== null);
     }
@@ -533,21 +531,11 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
     }
     const element = this.toXml(opt_noId);
     const xy = this.getRelativeToSurfaceXY();
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
     element.setAttribute(
-        'x',
-        Math.round(this.workspace.RTL ? width - xy.x : xy.x) as
-            AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    element.setAttribute('y', Math.round(xy.y) as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    element.setAttribute('h', this.getHeight() as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    element.setAttribute('w', this.getWidth() as AnyDuringMigration);
+        'x', String(Math.round(this.workspace.RTL ? width - xy.x : xy.x)));
+    element.setAttribute('y', String(Math.round(xy.y)));
+    element.setAttribute('h', String(this.getHeight()));
+    element.setAttribute('w', String(this.getWidth()));
     return element;
   }
 
@@ -588,16 +576,12 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
     const size = this.getHeightWidth();
 
     // Add text area
-    this.createEditor_();
-    // AnyDuringMigration because:  Argument of type 'SVGForeignObjectElement |
-    // null' is not assignable to parameter of type 'Node'.
-    this.svgGroup_.appendChild(this.foreignObject_ as AnyDuringMigration);
+    const foreignObject = this.createEditor_();
+    this.svgGroup_.appendChild(foreignObject);
 
     this.svgHandleTarget_ = dom.createSvgElement(
         Svg.RECT, {'class': 'blocklyCommentHandleTarget', 'x': 0, 'y': 0});
-    // AnyDuringMigration because:  Argument of type 'SVGRectElement | null' is
-    // not assignable to parameter of type 'Node'.
-    this.svgGroup_.appendChild(this.svgHandleTarget_ as AnyDuringMigration);
+    this.svgGroup_.appendChild(this.svgHandleTarget_);
     this.svgRectTarget_ = dom.createSvgElement(Svg.RECT, {
       'class': 'blocklyCommentTarget',
       'x': 0,
@@ -605,9 +589,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
       'rx': BORDER_RADIUS,
       'ry': BORDER_RADIUS,
     });
-    // AnyDuringMigration because:  Argument of type 'SVGRectElement | null' is
-    // not assignable to parameter of type 'Node'.
-    this.svgGroup_.appendChild(this.svgRectTarget_ as AnyDuringMigration);
+    this.svgGroup_.appendChild(this.svgRectTarget_);
 
     // Add the resize icon
     this.addResizeDom_();
@@ -671,10 +653,10 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
     textarea.readOnly = !this.isEditable();
     body.appendChild(textarea);
     this.textarea_ = textarea;
-    this.foreignObject_!.appendChild(body);
+    this.foreignObject_.appendChild(body);
     // Don't zoom with mousewheel.
     browserEvents.conditionalBind(
-        textarea, 'wheel', this, function(e: AnyDuringMigration) {
+        textarea, 'wheel', this, function(e: WheelEvent) {
           e.stopPropagation();
         });
     browserEvents.conditionalBind(
@@ -682,9 +664,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
         function(this: WorkspaceCommentSvg, _e: Event) {
           this.setContent(textarea.value);
         });
-    // AnyDuringMigration because:  Type 'SVGForeignObjectElement | null' is not
-    // assignable to type 'Element'.
-    return this.foreignObject_ as AnyDuringMigration;
+    return this.foreignObject_;
   }
 
   /** Add the resize icon to the DOM */
@@ -692,14 +672,10 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
     this.resizeGroup_ = dom.createSvgElement(
         Svg.G, {'class': this.RTL ? 'blocklyResizeSW' : 'blocklyResizeSE'},
         this.svgGroup_);
-    // AnyDuringMigration because:  Argument of type 'SVGGElement | null' is not
-    // assignable to parameter of type 'Element | undefined'.
     dom.createSvgElement(
         Svg.POLYGON,
         {'points': '0,x x,x x,0'.replace(/x/g, RESIZE_SIZE.toString())},
-        this.resizeGroup_ as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'SVGGElement | null' is not
-    // assignable to parameter of type 'Element | undefined'.
+        this.resizeGroup_);
     dom.createSvgElement(
         Svg.LINE, {
           'class': 'blocklyResizeLine',
@@ -708,9 +684,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
           'x2': RESIZE_SIZE - 1,
           'y2': RESIZE_SIZE / 3,
         },
-        this.resizeGroup_ as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'SVGGElement | null' is not
-    // assignable to parameter of type 'Element | undefined'.
+        this.resizeGroup_);
     dom.createSvgElement(
         Svg.LINE, {
           'class': 'blocklyResizeLine',
@@ -719,22 +693,18 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
           'x2': RESIZE_SIZE - 1,
           'y2': RESIZE_SIZE * 2 / 3,
         },
-        this.resizeGroup_ as AnyDuringMigration);
+        this.resizeGroup_);
   }
 
   /** Add the delete icon to the DOM */
   private addDeleteDom_() {
     this.deleteGroup_ = dom.createSvgElement(
         Svg.G, {'class': 'blocklyCommentDeleteIcon'}, this.svgGroup_);
-    // AnyDuringMigration because:  Argument of type 'SVGGElement | null' is not
-    // assignable to parameter of type 'Element | undefined'.
     this.deleteIconBorder_ = dom.createSvgElement(
         Svg.CIRCLE,
         {'class': 'blocklyDeleteIconShape', 'r': '7', 'cx': '7.5', 'cy': '7.5'},
-        this.deleteGroup_ as AnyDuringMigration);
+        this.deleteGroup_);
     // x icon.
-    // AnyDuringMigration because:  Argument of type 'SVGGElement | null' is not
-    // assignable to parameter of type 'Element | undefined'.
     dom.createSvgElement(
         Svg.LINE, {
           'x1': '5',
@@ -744,9 +714,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
           'stroke': '#fff',
           'stroke-width': '2',
         },
-        this.deleteGroup_ as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'SVGGElement | null' is not
-    // assignable to parameter of type 'Element | undefined'.
+        this.deleteGroup_);
     dom.createSvgElement(
         Svg.LINE, {
           'x1': '5',
@@ -756,7 +724,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
           'stroke': '#fff',
           'stroke-width': '2',
         },
-        this.deleteGroup_ as AnyDuringMigration);
+        this.deleteGroup_);
   }
 
   /**
@@ -867,17 +835,15 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
     const topOffset = WorkspaceCommentSvg.TOP_OFFSET;
     const textOffset = TEXTAREA_OFFSET * 2;
 
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    this.foreignObject_!.setAttribute(
-        'width', size.width as AnyDuringMigration);
-    this.foreignObject_!.setAttribute(
-        'height', (size.height - topOffset).toString());
+    this.foreignObject_?.setAttribute('width', `${size.width}`);
+    this.foreignObject_?.setAttribute('height', `${size.height - topOffset}`);
     if (this.RTL) {
-      this.foreignObject_!.setAttribute('x', (-size.width).toString());
+      this.foreignObject_?.setAttribute('x', `${- size.width}`);
     }
-    this.textarea_!.style.width = size.width - textOffset + 'px';
-    this.textarea_!.style.height = size.height - textOffset - topOffset + 'px';
+
+    if (!this.textarea_) return;
+    this.textarea_.style.width = size.width - textOffset + 'px';
+    this.textarea_.style.height = size.height - textOffset - topOffset + 'px';
   }
 
   /**
@@ -892,24 +858,16 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
     height = Math.max(height, 20 + WorkspaceCommentSvg.TOP_OFFSET);
     this.width_ = width;
     this.height_ = height;
-    this.svgRect_.setAttribute('width', width);
-    this.svgRect_.setAttribute('height', height);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    this.svgRectTarget_!.setAttribute('width', width as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    this.svgRectTarget_!.setAttribute('height', height as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    this.svgHandleTarget_!.setAttribute('width', width as AnyDuringMigration);
-    // AnyDuringMigration because:  Argument of type 'number' is not assignable
-    // to parameter of type 'string'.
-    this.svgHandleTarget_!.setAttribute(
-        'height', WorkspaceCommentSvg.TOP_OFFSET as AnyDuringMigration);
+    this.svgRect_.setAttribute('width', `${width}`);
+    this.svgRect_.setAttribute('height', `${height}`);
+    this.svgRectTarget_?.setAttribute('width', `${width}`);
+    this.svgRectTarget_?.setAttribute('height', `${height}`);
+    this.svgHandleTarget_?.setAttribute('width', `${width}`);
+    this.svgHandleTarget_?.setAttribute(
+        'height', `${WorkspaceCommentSvg.TOP_OFFSET}`);
     if (this.RTL) {
       this.svgRect_.setAttribute('transform', 'scale(-1 1)');
-      this.svgRectTarget_!.setAttribute('transform', 'scale(-1 1)');
+      this.svgRectTarget_?.setAttribute('transform', 'scale(-1 1)');
     }
 
     if (this.resizeGroup_) {
@@ -919,7 +877,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
             'transform',
             'translate(' + (-width + RESIZE_SIZE) + ',' +
                 (height - RESIZE_SIZE) + ') scale(-1 1)');
-        this.deleteGroup_!.setAttribute(
+        this.deleteGroup_?.setAttribute(
             'transform',
             'translate(' + (-width + RESIZE_SIZE) + ',' + -RESIZE_SIZE +
                 ') scale(-1 1)');
@@ -928,7 +886,7 @@ export class WorkspaceCommentSvg extends WorkspaceComment implements
             'transform',
             'translate(' + (width - RESIZE_SIZE) + ',' +
                 (height - RESIZE_SIZE) + ')');
-        this.deleteGroup_!.setAttribute(
+        this.deleteGroup_?.setAttribute(
             'transform',
             'translate(' + (width - RESIZE_SIZE) + ',' + -RESIZE_SIZE + ')');
       }
diff --git a/tests/mocha/workspace_comment_test.js b/tests/mocha/workspace_comment_test.js
index 0ea07b88b..1fe3bfc76 100644
--- a/tests/mocha/workspace_comment_test.js
+++ b/tests/mocha/workspace_comment_test.js
@@ -152,14 +152,14 @@ suite('Workspace comment', function() {
     });
 
     test('Initial position', function() {
-      const xy = this.comment.getXY();
+      const xy = this.comment.getRelativeToSurfaceXY();
       chai.assert.equal(xy.x, 0, 'Initial X position');
       chai.assert.equal(xy.y, 0, 'Initial Y position');
     });
 
     test('moveBy', function() {
       this.comment.moveBy(10, 100);
-      const xy = this.comment.getXY();
+      const xy = this.comment.getRelativeToSurfaceXY();
       chai.assert.equal(xy.x, 10, 'New X position');
       chai.assert.equal(xy.y, 100, 'New Y position');
     });