GH-1003 add some save locking for dialog pages that deal with settings

application/pages/global/MultiMCPage.cpp

@@ -247,6 +247,9 @@ void MultiMCPage::refreshUpdateChannelDesc()
 void MultiMCPage::applySettings()
 {
 	auto s = MMC->settings();
+
+	SettingsObject::Lock lock(s);
+
 	// Language
 	s->set("Language",
 		   ui->languageBox->itemData(ui->languageBox->currentIndex()).toLocale().bcp47Name());