Currently, Wikilink only has generic 500 error pages. These can be confusing for end users. We should create more informative error pages.

Acceptance Criteria

• Create error message templates, styling, logic for django-thrown errors
  • eg. In TWLight, we have templates for 4xx and 5xx errors, see numeric template files: https://github.com/WikipediaLibrary/TWLight/tree/master/TWLight/templates/ for reference.
• Create the 500.html template in such a way that it can be reused by nginx as a fallback error page
  • nginx can be configured to access the static resources used in the dynamic django pages
  • see this search for more context https://github.com/WikipediaLibrary/TWLight/blob/25a171838c5eb49390ff9baf6ca789970991fe2e/TWLight/templates/500/500.html#L4