I've reproduced the problem, but need to investigate the bug to get it fixed.
It is probably due to concurrency of two or more requests and the problem may not be easy to solve.
This is my best offer.
I'm a senior software developer, have a good experience with QT4/5 and ha a great experience with networking programming, multithreading, concurrency and problems involved.
Of course I can get the sources, complile them, and undestnad where is the problem that makes it crash.
I can guarantee an european standard of quality, I'm not an aian develper.
I'm availabe in chat is you want to duscuss.