fix(sentry#6931306293): fix issue with url context resolver

[JacobCoffee]

Description

• When browsing somewhere nonexistent we crash and throw a Sentry error:
  https://www.python.org/search/?q=about&page=45 leads to:

which fails loading JS and the title bar is also funky:

---

(InteractiveConsole) >>> from django.test import RequestFactory >>> >>> from pydotorg import context_processors >>> >>> factory = RequestFactory() File "<console>", line 1 factory = RequestFactory() IndentationError: unexpected indent >>> factory = RequestFactory() >>> request = factory.get('/this-does-not-exist/') >>> result = context_processors.url_name(request) >>> print(result) {'URL_NAMESPACE': None, 'URL_NAME': None} >>> request = factory.get('/about/') >>> result = context_processors.url_name(request) >>> >>> print(result) {'URL_NAMESPACE': '', 'URL_NAME': 'about'} >>> 

testing locally we get the right context:

Closes

• Fixes AttributeError: 'NoneType' object has no attribute 'engine' #2792