Export to csv - App breaks down #809

Steps to reproduce the behaviour

1. Pick Menu Export,
   export to file/owncloud/mail (same behaviour for all)
   format csv
   time from 01.01.2019
   delete transactions after export: no
   repeat: none

Tip "Exportieren"

Expected behaviour

A file is created in csv-format

Actual behaviour

gnu-cash breaks down, Application halted
no file created.
whenn i pick export to "speichern unter" there is a file created, but empty.

Software specifications

• GnuCash Android version: 2.4.0
• System Android version: 6.0.1
• Device type: FP 2 (FairPhone)