GTFS+ downloads fails on Firefox

GTFS+ editor state is left uninitialized in Firefox when viewing/editing GTFS+ files.
(This issue does not occur in Chromium/WebKit browsers).

<img width="923" alt="Image" src="https://github.com/user-attachments/assets/acd4c65e-5d90-44b0-81b5-14f8a0194da1" />