fix: dont add comments to full block fields (#9263)

* fix: dont add comments to full block fields

* chore: remove some nonnull assertions

core/block.ts

@@ -1118,7 +1118,7 @@ export class Block {
    *
    * @yields A generator that can be used to iterate the fields on the block.
    */
-  *getFields(): Generator<Field> {
+  *getFields(): Generator<Field, undefined, void> {
     for (const input of this.inputList) {
       for (const field of input.fieldRow) {
         yield field;

core/contextmenu_items.ts

@@ -25,6 +25,12 @@ import {StatementInput} from './renderers/zelos/zelos.js';
 import {Coordinate} from './utils/coordinate.js';
 import type {WorkspaceSvg} from './workspace_svg.js';
 
+function isFullBlockField(block?: BlockSvg) {
+  if (!block || !block.isSimpleReporter()) return false;
+  const firstField = block.getFields().next().value;
+  return firstField?.isFullBlockField();
+}
+
 /**
  * Option to undo previous action.
  */
@@ -362,10 +368,15 @@ export function registerComment() {
     preconditionFn(scope: Scope) {
       const block = scope.block;
       if (
-        !block!.isInFlyout &&
-        block!.workspace.options.comments &&
-        !block!.isCollapsed() &&
-        block!.isEditable()
+        block &&
+        !block.isInFlyout &&
+        block.workspace.options.comments &&
+        !block.isCollapsed() &&
+        block.isEditable() &&
+        // Either block already has a comment so let us remove it,
+        // or the block isn't just one full-block field block, which
+        // shouldn't be allowed to have comments as there's no way to read them.
+        (block.hasIcon(CommentIcon.TYPE) || !isFullBlockField(block))
       ) {
         return 'enabled';
       }
@@ -373,8 +384,8 @@ export function registerComment() {
     },
     callback(scope: Scope) {
       const block = scope.block;
-      if (block!.hasIcon(CommentIcon.TYPE)) {
-        block!.setCommentText(null);
+      if (block && block.hasIcon(CommentIcon.TYPE)) {
+        block.setCommentText(null);
       } else {
         block!.setCommentText('');
       }