Query Designer: the screen should be locked on execution

Version 38.1
http://api.ugene.net/tools/ugenecrashes/index.php?id=24025
Crash "devided by zero".

The fact is that in the Query Designer you can start the execution of the scheme, and then delete the element to the screen. During execution, for all sorts of needs, calls to objects that designate elements periodically occur - and they have already been deleted and destroyed.

Dmitrii analyzed the report and decided that this crash happened somewhere in QDScheduler.cpp either on 62 or 64 lines - there, to set the progress, the bar status is divided by the number of elements on the scene, and, apparently, the elements were deleted ( probably just one element was and it was removed) and division by zero occurred.

Possible solusion: Do it like in the Workflow Designer - there the screen is simply locked at startup.