JSONError inheriting from HTTPError causes named error with details

[fmigneault]

Somewhat like #275, but since it dates from 2015, things changed a lot in the code.

Because cornice.renderer.JSONError inherits from pyramid.httpexceptions.HTTPError, its __str__ implementation looks for the detail attribute. A simple logging call such as logger.info("exception: {!s}", err) is enough to cause this exception to crash.

The HTTPException itself the following:

    def __str__(self):
        return str(self.detail) if self.detail else self.explanation

So either the JSON body could be set to detail and let it represent it as plain string, or define detail/explanation accordingly with some more explicit message.

[fmigneault]

The cause is related to this initialization call:

cornice/src/cornice/renderer.py

Lines 13 to 18 in abfcfd9

	class JSONError(exc.HTTPError):
	def __init__(self, serializer, serializer_kw, errors, status=400):
	body = {"status": "error", "errors": errors}
	Response.__init__(self, serializer(body, **serializer_kw))
	self.status = status
	self.content_type = "application/json"

Because the Response.__init__ is called rather than HTTPError.__init__, not all attributes expected by this class get properly assigned, and notably, the detail attribute that is defined only under HTTPError, and not Response.

[fmigneault]

@leplatrem Is it possible to see if replacing the base class __init__ call is sufficient to fix this issue?