Add nice 404 page

[Tom-van-Woudenberg]

To be compatible with: https://github.com/TeachBooks/deploy-book-workflow/pull/39 @severinbratus, am I correct that the current 404 page is described here: https://github.com/TeachBooks/deploy-book-workflow/blob/dc47d34ae3211fad64b30e55661162d923729551/.github/workflows/deploy-book.yml#L463 and that the current 404.html and 404.md can be deleted? Is it possible to use this default 404 page only if no custom 404 page is provided on the root of the repo to be in line with the github documentation?

[severinbratus]

Yes, that is correct. Yes, this should be possible. I see two tasks to do here:

• [ ] Make a better default 404 page (e.g. also with a list of deployed branches, or a link to the latest successful summary)
• [ ] Use the 404.html in the root dir if provided

[AleksSliw]

I am editing the template for the generated 404 page and a question popped up. What should be the expected behaviour for 404 redirect? inputting a wrong URL in the form of valid-repository/wrong-name will redirect to valid-repository/main/wrong-name (which is still invalid and will show 404), while inputting valid-repository/right-branch/wrong-name will just show the 404 page with that same URL.

Im assuming the idea is to redirect to the main branch if the repository exists?

[Tom-van-Woudenberg]

I think the 404 page should never redirect, only show a button to bring you to the root of valid-repository There'll always be a page on root.