Close#24002
Two problems before:
1. The `log.Fatal` is missing after these `wrapFatal` calls, so the
error is not shown to users.
2. `GetTemplateAssetNames` has different behaviors for local files and
builtin assets, for builtin assets, it also returns directories, so we
need to check the extension again.
I have tested with `TAGS="bindata sqlite sqlite_unlock_notify" make
build && ./gitea` , it works well now. Before, the server responds
internal server error (because it doesn't complete the template parsing)