If there is an exception thrown in a webservice apart from the core rest webservice, Whoops overrides the exception name, for example:

{

    "exception": "Whoops\\Exception\\ErrorException",

    "message": "Attempt to read property \"quizid\" on array"

}

I noticed this when using webservice_restful ( https://github.com/catalyst/moodle-webservice_restful )

I'm not 100% sure why this does not affect the core Rest webservice (I have not tested soap), but nevertheless I think Whoops should never activate when using webservices, as it was originally intended only for web requests.

Adding

|| WS_SERVER

here https://github.com/moodle/moodle/blob/f30110b5ebf9090ee484986e020d43a7819fc436/lib/setuplib.php#L354

appears to fix it