[RFC] Coverity Issues

This PR fixes several Coverity issues listed in #760 , namely 13796, 62607, 62608, 62609, 62612, 62615. Additionally I found that some of the Coverity defects are false positives, especially in the ressource leak category.

I couldn't find how to mark them as false positives in the Coverity web interface though. I suspect that my role of contributer doesn't have sufficient rights to do so.
do we want to keep that behaviour or does it make more sense to just error out if it is not possible to replace all lines?