Looks fine in light mode, text unreadable in dark mode.

Describe the bug
When exporting annotation with Flashcard, the JSON line is undefined

    },
    undefined,
    {

To Reproduce
Steps to reproduce the behavior:

1. Annotate a line of text
2. Add a Flashcard with data on back and front
3. Export annotation as JSON
4. Search "undefined" you should get to that badly exported entry

Expected behavior

Fla

To prevent regressions like #2280, we should add more unit tests for file loading / saving.

Is it possible to provide a prebuilt installation. Maybe even with a gui to install?
I'm using a shared hosting service and the possibilities to built codimd on the server are very limited.