Create generic 500 page

**Is your feature request related to a problem? Please describe.**
Sometimes errors can't be displayed properly on a specific page, we should have a generic error page that can accept a custom error message to display. For example, when middleware functions fail, we may want to send the user to an error page, instead of attempting to load the next page with a mangled request.

**Describe the solution you'd like**
Create a generic 500.html error page/template that accepts a message that simply gets displayed on the page.

**Describe alternatives you've considered**
None

**Additional context**
None