DEBUG version crashes when opening Format > Page Settings on a part
In a selfbuild MuseScore in DEBUG mode (like QtCreator/MinGW) and a score with parts open the Format > Pagesetting dialog for a part.
Result; crash/abort due to a failed assertion in libmscore/xml.h, line 275
This gets called only once in the source, from libmscore/element.cpp, line 565
While there is no crash in and non-DEBUG version, this failed assertion should indicate that there is a problem, even if it seems to have no further consequences. like it would write a most probably bogus value for
indexDiff into the score.
I stumbled accross this while working in a fix for #300279: Impossible to apply properties to all parts in 3.4.1