Crashlog
If the app closes unexpectedly, it has likely "crashed". This should hopefully happen extremely rarely, but can usually be fixed quickly once the developer gets the crash log.
Crash logs contain no personal data — they only record the exact point in the software where things went wrong.
iOS Settings
a) Share Automatically
In this case, no further action is needed. The developers of all apps automatically receive crash logs once a day through Apple when a crash occurs.
b) Share Manually
Under "Analytics Data" you'll find crash logs for all apps. The filename includes the name of the app and the timestamp. These files can be shared individually — for example Feedback.