TypeScript: Types for CommandManager.on's callback's arguments were lost between 1.36.5 and 1.37.5

[shepmaster]

Describe the bug / Current Behavior

Code like editor.commands.on('afterExec', ({ editor, command }) => { /* ... */ }) no longer knows the type of editor (Ace.Editor) or command (Ace.Command).

Expected Behavior

Code like editor.commands.on('afterExec', ({ editor, command }) => { /* ... */ }) knows the type of editor (Ace.Editor) or command (Ace.Command).

Reproduction Steps

Create a basic TypeScript project

tsconfig.json

{
  "compilerOptions": {
    "target": "es2016",
    "module": "commonjs",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true
  }
}

package.json

{
  "name": "repro",
  "version": "1.0.0",
  "description": "",
  "main": "index.ts",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "ace-builds": "1.36.5",
    "typescript": "^5.7.3"
  }
}

index.ts

import { Ace } from 'ace-builds';

// ==========
// https://stackoverflow.com/a/58779181/155423
type IsAny<T> =
  unknown extends T ? T extends {} ? T : never : never;

type NotAny<T> =
  T extends IsAny<T> ? never : T;

function notAny<T>(x: NotAny<T>) { }
// ==========

function example(editor: Ace.Editor) {
  editor.commands.on('afterExec', ({ editor, command }) => {
    notAny(editor);
    notAny(command);
  });
}

Run the project

pnpm tsc index.ts

Upgrade to 1.37.5, run project again

pnpm tsc index.ts

index.ts:16:12 - error TS2345: Argument of type 'any' is not assignable to parameter of type 'never'.

16     notAny(editor);
              ~~~~~~

index.ts:17:12 - error TS2345: Argument of type 'any' is not assignable to parameter of type 'never'.

17     notAny(command);
              ~~~~~~~

Possible Solution

No response

Additional Information/Context

Going only by the changelog entry, the changes from @mkslanc in #5427 seem likely to be relevant.

Ace Version / Browser / OS / Keyboard layout

Ace 1.37.5 / TypeScript 5.7