Bug: closing MuseScore with no scores open crashes

Steps to repeat:
Open MuseScore (the latest master/nightly build) close all open scores. Close MuseScore any way you like. Crash occurs here, apparently because scoreList is empty, zero elements:

https://github.com/musescore/MuseScore/blob/master/mscore/musescore.cpp…

Here is the call stack:
{syntaxhighlighter SPEC}
0 Ms::Score::masterScore score.h 933 0xc1ca64
1 Ms::MuseScore::writeSettings musescore.cpp 2765 0x48dcb5
2 Ms::MuseScore::closeEvent musescore.cpp 288 0x47e3a2
3 ZN7QWidget5eventEP6QEvent 0x1a70c901
4 I_CryptInstallAsn1Module 0x76c4559f
{/syntaxhighlighter}