Add documentation for debug error handling

[Lunrtick]

This is a first attempt at documenting the error handling with DEBUG on or off, as discussed in #619

[vitalik]

@Lunrtick thank you

I was actually thinking to add extra check - do not shallow exception if ATOMIC_REQUESTS is set (which I think is not for 95% users)

[Lunrtick]

That could definitely work. It would also mean that the user wouldn't get a stack trace back.

They could of course look in the terminal to see the error, so I suppose it doesn't matter too much either way.

Thinking about it now, maybe a Django middleware that comes as an optional extra with django-ninja would be the right way to go. You could keep lines 107 and 108 here and remove lines 109-112.

django-ninja/ninja/errors.py

Lines 104 to 112 in e5e3a4c

	def _default_exception(
	request: HttpRequest, exc: Exception, api: "NinjaAPI"
	) -> HttpResponse:
	if not settings.DEBUG:
	raise exc # let django deal with it
	logger.exception(exc)
	tb = traceback.format_exc()
	return HttpResponse(tb, status=500, content_type="text/plain")

Instead, the logic could be

if not settings.DEBUG: 
    raise exc  # let django deal with it
else:
    raise NinjaAPIException() from exc 

Or even just

raise NinjaAPIException() from exc 

and then the middleware would be something simple like

# catch NinjaAPIException
if settings.DEBUG:
    return 500, {"a nice": "stack trace"}
else:
    raise exc

This would mean that ATOMIC_REQUESTS should work as expected either way.