Fix admin config page error, use tests to cover the admin config and 500 error page (#24965)
The admin config page has been broken for many many times, a little
refactoring would make this page panic.
So, add a test for it, and add another test to cover the 500 error page.
Co-authored-by: Giteabot <teabot@gitea.io>
Change all license headers to comply with REUSE specification.
Fix #16132
Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
wxiaoguang
flynnnnnnnnnn
Ethan Koenig
Lunny Xiao