When enough documentations are stored offline, so that the sqlite file reaches about 50 MB, the web app is not able to access it anymore. The interface is fully functional, but opening the Offline tab results in the message

Oops, the database failed to load.

This also prevents the user from resetting the app.
After deleting the storage files in [Profile_directory]/storage/default, the app is fully functional again.
The web app was created using Firefox Developer Edition 37.0a2, however the web version on the same browser has no such size limitation.