This corruption can occur when a device overheats, runs out of battery, crashes for some other reason.
As a result, LapTimer fails to open or access data or other configuration and runs into an unexpected condition.
The first rule in case this happens: do not try the uninstall / reinstall approach. LapTimer stores data locally, deleting the app will purge that data (and videos) too.
Instead, a so called emergency startup needs to be triggered.
- On iOS, goto Settings app and find LapTimer. Navigate to Expert Settings and set "Emergency Startup" to ON. Both items are (almost) in the bottom of the respective screen.
- On Android, settings cannot be accessed while the app is not running. Instead, open this URL on your smartphone: http://gps-laptimer.de/laptimer/emergencystartup Whether opening this link fires up LapTimer or Chrome or show a selection, depends on your device configuration. In case Chrome is coming up immediately (with a 404 message), you need to enable the link for LapTimer first.
- For Android 12 and later, goto Settings app ‣ Apps ‣ Default Apps ‣ Opening Links ‣ LapTimer. Tick "Open supported links" and add "gps-laptimer.de" to the list in the bottom. Touching the above link in Chrome may still bring you to the page with 404. In case this happens, I recommend to copy the link above, paste it into a mail open open the link from this mail once it arrives. I'm sure there are better options, but this is the one I found working.
- For other Android versions, navigation may differ.