QLocale::uiLanguages() crashes on Mac

Users of a Qt application are reporting a crash at startup which is related to QLocale::uiLanguages(). A user having just English in his list fixed the crash by adding Polish in the System Preferences.

Here's a reported trace:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 com.apple.CoreFoundation 0x92faa751 CFArrayGetCount + 17
1 com.digia.qt.QtCore 0x009a30e4 QSystemLocale::query(QSystemLocale::QueryType, QVariant) const + 4336
2 com.digia.qt.QtCore 0x009e089b QLocale::uiLanguages() const + 137
3 com.digia.qt.QtCore 0x00aaf85e QTranslator::load(QLocale const&, QString const&, QString const&, QString const&, QString const&) + 362