Api site has confusing 404-error page.

[lrhn]

Try an unsupported link like https://api.dart.dev/3.0.0/dart-core/.
The 404 page has bad formatting, multiple inert search boxes, and links at the bottom that don't actually work.

(I was guessing at how to get to older docs. That wasn't it.)

[Franklyn-R-Silva]

I have submitted a fix for this in the dartdoc repository, which handles the 404 error page template.

The fix removes the inert search boxes and cleans up the formatting as suggested. You can follow the progress here: 4139