Gitea Web frontend broken since ~2 weeks

[gsantner]

• Gitea version (or commit ref): ba1acf5
• Git version: 2.17.1
• Operating system: U18.04
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
  • Not relevant
• Log gist:

Description

Since about beginning of december the web frontend of Gitea seems to be completely broken.
I can login but nearly cannnot click anything and most stuff doesn't render.
Additionally from browser log I see that some css/js files are served as html which sould be also relevant.

I'm using the builds from https://dl.gitea.io/gitea/master/gitea-master-linux-amd64 since long time and had never such problems.. I have a older version of gitea locally (2019-11-28) where everything works still works as it should, so it's no webserver issue. But seems like all newer builds are broken due some recent changes.

See screenshots:

Screenshots

[silverwind]

Duplicate of #9324