Implement waiting for prtcl.svg data in a working way

47ae0cec proposed a fix, that doesn't work at all.

Steps to reproduce sometimes:

1. Ensure you are logged in to GitLab and have access to the Protocols repo
2. Open the /fachschaftssitzung route
3. Reload with Ctrl+F5
4. However over the protocol links, they will likely (bug!) lead to 0000-00-00.md

When reloading with F5, it takes one or two attempts, after the app will correctly show the right link.