fix: Handle exceptions raised when fetching Django request data

[davidwtbuxton]

The Django helper calls request.build_absolute_uri(), but that may raise a DisallowedHost exception itself. Instead we catch any exception and log None as the URL.

Fixes #757

[davidwtbuxton]

Hi,

I have tested this on the App Engine app that was showing errors, and I no longer see the errors. Which is a good thing.

I'm not sure that my fix of catching any Exception is correct, because it is overly broad. We could catch the specific django.core.exceptions.DisallowedHost exception that is raised by request.build_absolute_uri(), but that would involve importing the exception from Django. Or we could catch Exception and check the doc string. But that then ties us to the docstring. Something like this:

try:
    request_url = request.build_absolute_uri()
except Exception as err:
    if err.__doc__ == "HTTP_HOST header contains invalid value":
        request_url = None
    else:
        raise

Also I figured setting request_url = None and letting the logging request complete with incomplete data was more useful than causing an uncaught exception further up the stack.

[daniel-sanche]

Thanks for putting this together!