Don't break when trying to check if TemplateHooks apply on 404s.
On 404 pages, the request doesn't have a resolver_match. For TemplateHooks

that apply to base.html (like the base-css hook point, for example), this

was problematic because 404.html extends base.html, and so any TemplateHook

that injects itself in a base hook point on only certain pages would cause

breakages since the resolver_match couldn't be checked to see if the

TemplateHook should actually apply.

I'm not exactly sure how to test this just yet because I'm having difficulty testing

the 404 page since that requires DEBUG = False, and I'm getting 500's on my dev server

any time I try to browse to any page. :/