Exceptions in async controller action not caught by stimulus

Stimulus doesn't catch exceptions thrown from async controller actions. This means that

a) We don't get nice stimulus errors in the console
b) handleError is never called, so overriding it (e.g. to log errors to a monitoring system like Sentry or Azure App Insights) has no effect.

This happens because the call to user code (this.method.call(this.controller, actionEvent)) is not awaited, so it returns a Promise immediately, and escapes the try catch block.

https://github.com/hotwired/stimulus/blob/5fd12c7b6af88620741e3aa969b6ab440559c5b7/src/core/binding.ts#L74-L84

I think something like this would work:

  invokeWithEvent(event) {
    function handleError(error) {
      const { identifier, controller, element, index } = this;
      const detail = { identifier, controller, element, index, event };
      this.context.handleError(error, `invoking action "${this.action}"`, detail);
    }

    const { target, currentTarget } = event;
    try {
      const { params } = this.action;
      const actionEvent = Object.assign(event, { params });
      Promise.resolve(this.method.call(this.controller, actionEvent)).catch(error => handleError(error));
      this.context.logDebugActivity(this.methodName, { event, target, currentTarget, action: this.methodName });
    } catch (error) {
      handleError(error);
    }
  }

I think this is really important, because without the ability to configure custom error handling that applies to all stimulus controller code, users running production apps wont have visibility into how their async actions are failing, without putting a try catch block into every one of those methods.

Read src/core/binding.ts around the linked invokeWithEvent implementation, focusing on how the controller method is invoked and how errors reach handleError. Verify the behavior for both synchronous and asynchronous exceptions, and confirm that async failures produce the expected console error and invoke custom error handling.