Built in Custom Commands are invoked with wrong parameters if callback throws exception

Version 1.1.0-6

Module (core, cmpapi, cli, stub, or testing) cmpapi

Describe with reproduction steps – What is the expected behavior? Code to reproduce the issue:

import { CmpApi } from '@iabtcf/cmpapi';

const api = new CmpApi(123, 456, true, {
  addEventListener: (next, tcData, success) => {
    if (tcData) {
      tcData.someProp = 'some value';
    }

    if (typeof next === 'function') {
      next(tcData, success);
    } else {
      console.error('next is not a function');
    }
  },
});

api.update('', false);

window.__tcfapi('addEventListener', 2, (tcData, success) => {
  console.log('before exception', tcData, success);
  throwExceptionWithNonExistingFunction();
  console.log('after exception', tcData, success);
});

Current behaviour:

• next is not a function is logged

Expected behaviour (which is what happens if no built-in custom command is specified):

• before exception {...} true is logged
• before exception null false is logged
• Uncaught ReferenceError: throwExceptionWithNonExistingFunction is not defined error is logged

Considerations:

1. TCF API spec does not define what should be the behaviour in case the __tcfapi callback throws exception, currently the callback is invoked twice: first with right tcData and success === true, then with null tcData and success === false. It makes sense but the side effect is that the callback is invoked twice, maybe there should be some official spec on how __tcfapi should behave in case of callback’s exception, or at least specify that it’s up to the consumer to try...catch the callback as the __tcfapi behaviour could not be reliable in case of exceptions
2. I think built-in custom commands should always be invoked with next as a function, we have another similar case where they are invoked with only tcData and success as parameters, which I guess this PR should solve: https://github.com/InteractiveAdvertisingBureau/iabtcf-es/pull/212 (e.g. __tcfapi('getTCData', 2, function(tcData, success) {}, null))
3. this should be the code that exposes the issue: https://github.com/InteractiveAdvertisingBureau/iabtcf-es/blob/b4152095ebc3b494d5e69aebf32c608b6a6ecf4d/modules/cmpapi/src/command/Command.ts#L22-L30

[matita]

@chrispaterson I might be wrong, but I think it would just be a matter of changing this code: https://github.com/InteractiveAdvertisingBureau/iabtcf-es/blob/b4152095ebc3b494d5e69aebf32c608b6a6ecf4d/modules/cmpapi/src/command/Command.ts#L35-L55

into this code:

  protected invokeCallback(response: any): void {

	const success = response !== null;

    if (typeof this.next === 'function') {

      this.callback(this.next, response, success);

    } else {

      this.callback(response, success);

    }

  }

[shortaflip]

v1.2.1 of the library that contains the changes from the PR that closed this ticket is live.