QmlProject: Fix issue where qmlviewer is launched with directory as argument

This happened when 'Current File' was set in the settings, but no .user.settings
existed.

src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp

@@ -63,6 +63,7 @@ const char * const M_CURRENT_FILE = "CurrentFile";
 QmlProjectRunConfiguration::QmlProjectRunConfiguration(QmlProjectTarget *parent) :
     ProjectExplorer::RunConfiguration(parent, QLatin1String(Constants::QML_RC_ID)),
     m_qtVersionId(-1),
+    m_scriptFile(M_CURRENT_FILE),
     m_projectTarget(parent),
     m_usingCurrentFile(true),
     m_isEnabled(false)