Description: Fix a crash on reading a workspace with non-existing preferences
Author: Dmitri Ovodok <dmitrio95@yandex.ru>
Origin: upstream, commit:b9bb0ceb8223866f5b60f4d821b5b3544ffa4788
Applied-Upstream: master, commit:6c0bef1

--- a/mscore/preferences.cpp
+++ b/mscore/preferences.cpp
@@ -219,7 +219,7 @@ QVariant Preferences::defaultValue(const
       {
       checkIfKeyExists(key);
       Preference* pref = _allPreferences.value(key);
-      return pref->defaultValue();
+      return pref ? pref->defaultValue() : QVariant();
       }
 
 QSettings* Preferences::settings() const