message: Bugfix: Check document existence before revoking work.
diff: @@ -25,7 +25,10 @@ export class BaseWork {
  }
  public stop(): Promise<void> {
  + // Make sure the document is loaded first.
  + if (this.document !== undefined) {
  this.document.removeListener("op", this.operation);
  + }
  return Promise.resolve();
  }
  }
  