ReactiveX/rxjs · error · TypeError

Subscriber.addTeardown requires a callback

Error message

Subscriber.addTeardown requires a callback

What it means

Error "Subscriber.addTeardown requires a callback" thrown in ReactiveX/rxjs.

Source

Thrown at packages/observable-polyfill/src/index.ts:195

    }

    if (hasError) {
      throw firstError;
    }
  }

  get active(): boolean {
    return !this.#closed;
  }

  get signal(): AbortSignal {
    return this.#abortController.signal;
  }

  addTeardown(teardown: () => void): void {
    this.#assertBrand();
    if (arguments.length === 0 || typeof teardown !== 'function') {
      throw new TypeError('Subscriber.addTeardown requires a callback');
    }

    if (!this.active) {
      teardown();
      return;
    }

    this.#teardowns.push(teardown);
  }

  next(value: T): void {
    this.#assertBrand();
    if (arguments.length === 0) {
      throw new TypeError('Subscriber.next requires a value');
    }

    if (this.active) {
      const observers = Array.from(this.#observerList);

View on GitHub (pinned to 54796b38a5)

When it happens

Trigger: Thrown at packages/observable-polyfill/src/index.ts:195 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of ReactiveX/rxjs@54796b38a5 (2026-08-28). Data as JSON: /api/errors/63907a9e1f878632. Report an issue: GitHub.