Invoking the Github creation API as a user that lacks the "create job" permission returns a 403 error with the response body as a HTML page with the following content:

<h1>Access Denied</h1>

<p class="error">axltorvalds is missing the Job/Create permission</p>

It should instead return a JSON response body with the appropriate errorCode and message properties populated.

Eventually we will probably hide the entire Creation UI from users that lack the right role / permission so this is probably not a major issue from the UI's standpoint.