hunk.code_window:     let subscription: Subscription;
       this.schedule(() => {
         subscription = observable.subscribe(
           (x) => {
             // Support Observable-of-Observables
             const value = x instanceof Observable ? this.materializeInnerObservable(x, this.frame) : x;
             actual.push({ frame: this.frame, notification: nextNotification(value) });
           },
  
hunk.labels: keep keep keep replace replace keep keep keep keep
hunk.after_edit:       subscription = observable.subscribe({
           next: (x) => {
  
hunk.file_path: src/internal/testing/TestScheduler.ts
hunk.type: replace
file: import { createErrorClass } from './createErrorClass';
  
  export interface UnsubscriptionError extends Error {
    readonly errors: any[];
  }
  
  export interface UnsubscriptionErrorCtor {
    /**
     * @deprecated Internal implementation detail. Do not construct error instances.
     * Cannot be tagged as internal: https://github.com/ReactiveX/rxjs/issues/6269
     */
    new (errors: any[]): UnsubscriptionError;
  }
  
  /**
   * An error thrown when one or more errors have occurred during the
   * `unsubscribe` of a {@link Subscription}.
   */
  export const UnsubscriptionError: UnsubscriptionErrorCtor = createErrorClass(
    (_super) =>
      function UnsubscriptionErrorImpl(this: any, errors: (Error | string)[]) {
        _super(this);
        this.message = errors
          ? `${errors.length} errors occurred during unsubscription:
  ${errors.map((err, i) => `${i + 1}) ${err.toString()}`).join('\n  ')}`
          : '';
        this.name = 'UnsubscriptionError';
        this.errors = errors;
      }
  );
  