Despite several friendly reminder on my part to troubleshoot, it is by now almost 1.5 months at the promise to take care of the problem remained.
Addendum: The bug is device- or androidversions-dependent. On my phone (Sony Xperia model C2105, Android 4.2.2), the error occurs. On my Chinese Tab (NovoCrystal, Android 4.1.1) on the other is not running, so there are no other problems (eg, Chrome), the app is running properly and the error described does not occur.