diff --git a/core/procedures/observable_parameter_model.ts b/core/procedures/observable_parameter_model.ts
index 4c74a0505..9255037e1 100644
--- a/core/procedures/observable_parameter_model.ts
+++ b/core/procedures/observable_parameter_model.ts
@@ -17,7 +17,8 @@ export class ObservableParameterModel implements IParameterModel {
   constructor(
       private readonly workspace: Workspace, name: string, id?: string) {
     this.id = id ?? genUid();
-    this.variable = workspace.createVariable(name);
+    this.variable =
+        this.workspace.getVariable(name) ?? workspace.createVariable(name);
   }
 
   /**
@@ -34,12 +35,14 @@ export class ObservableParameterModel implements IParameterModel {
    * Unimplemented. The built-in ParameterModel does not support typing.
    * If you want your procedure blocks to have typed parameters, you need to
    * implement your own ParameterModel.
+   *
+   * @throws Throws for the ObservableParameterModel specifically because this
+   *     method is unimplemented.
    */
   setTypes(_types: string[]): this {
-    console.warn(
+    throw new Error(
         'The built-in ParameterModel does not support typing. You need to ' +
         'implement your own custom ParameterModel.');
-    return this;
   }
 
   /**
diff --git a/core/procedures/observable_procedure_map.ts b/core/procedures/observable_procedure_map.ts
index db5edfe68..35ee4a5e7 100644
--- a/core/procedures/observable_procedure_map.ts
+++ b/core/procedures/observable_procedure_map.ts
@@ -17,7 +17,7 @@ export class ObservableProcedureMap extends Map<string, IProcedureModel> {
    * Adds the given procedure model to the procedure map.
    */
   override set(id: string, proc: IProcedureModel): this {
-    // TODO(#6156): Fire events.
+    // TODO(#6516): Fire events.
     super.set(id, proc);
     return this;
   }
@@ -27,7 +27,7 @@ export class ObservableProcedureMap extends Map<string, IProcedureModel> {
    * exists).
    */
   override delete(id: string): boolean {
-    // TODO(#6156): Fire events.
+    // TODO(#6516): Fire events.
     return super.delete(id);
   }
 
@@ -35,7 +35,7 @@ export class ObservableProcedureMap extends Map<string, IProcedureModel> {
    * Removes all ProcedureModels from the procedure map.
    */
   override clear() {
-    // TODO(#6156): Fire events.
+    // TODO(#6516): Fire events.
     super.clear();
   }
 
@@ -44,7 +44,8 @@ export class ObservableProcedureMap extends Map<string, IProcedureModel> {
    * blocks can find it.
    */
   add(proc: IProcedureModel): this {
-    // TODO(#6156): Fire events.
+    // TODO(#6516): Fire events.
+    // TODO(#6526): See if this method is actually useful.
     return this.set(proc.getId(), proc);
   }
 }