Changed NoteSkinManager to use new error reporting and avoid crashing. Fixed DoChangeTheme to switch to the InitialScreen if the screen doesn't exist in the theme being changed to. Fixed error reporting in MeterDisplay.

src/ScreenManager.cpp

@@ -722,6 +722,11 @@ void ScreenManager::LoadDelayedScreen()
 {
 	RString sScreenName = m_sDelayedScreen;
 	m_sDelayedScreen = "";
+	if(!IsScreenNameValid(sScreenName))
+	{
+		LuaHelpers::ReportScriptError("Tried to go to invalid screen: " + sScreenName, "INVALID_SCREEN");
+		return;
+	}
 
 	// Pop the top screen, if any.
 	ScreenMessage SM = PopTopScreenInternal();