Method addObserver

packages/effect/src/internal/fiberRuntime.ts:535–541

* Adds an observer to the list of observers. * * **NOTE**: This method must be invoked by the fiber itself.

(observer: (exit: Exit.Exit<A, E>) => void)

   * **NOTE**: This method must be invoked by the fiber itself.
   */
  addObserver(observer: (exit: Exit.Exit<A, E>) => void): void {
    if (this._exitValue !== null) {
      observer(this._exitValue!)
    } else {
      this._observers.push(observer)
    }
  }

  /**
   * Removes the specified observer from the list of observers that will be