Help, please, running MuseScore from Xcode

I'm trying to run MuseScore from Xcode, but having no luck. It runs for a while, and I can step through main() in mscore, but it reaches line 6570 of mscore


if (!converterMode && !pluginMode) {
if (!argv.isEmpty()) {

and just steps into the "else" branch and exits. I've turned off the debug flag. Any idea what I could be doing wrong? I'm new both to MuseScore and Xcode. Xcode 9.4.1, and I think its the 3.0 development branch of MuseScore that I cloned from gitHub.

The Xcode console shows the following:

warning: 'QtCore' contains a debug script. To run this script in this debug session:

command script import "/Users/jerry/codeprojects/Qt/5.11.2/clang_64/lib/QtCore.framework.dSYM/Contents/Resources/DWARF/../Python/QtCore.py"

settings set target.load-script-from-symbol-file true

command script import "/Users/jerry/codeprojects/Qt/5.11.2/clang_64/lib/QtCore.framework.dSYM/Contents/Resources/DWARF/../Python/QtCore.py"

settings set target.load-script-from-symbol-file true

2018-08-31 21:34:19.837323-0700 mscore[76105:3460334] flock failed to lock maps file: errno = 35
2018-08-31 21:34:19.838692-0700 mscore[76105:3460334] flock failed to lock maps file: errno = 35
(lldb)

The two flock errors were thrown at line #6373:


MuseScoreApplication* app = new MuseScoreApplication(appName2, argc, av);


Thanks for any help with this.