Make blank project name create an error, not a warning

(cherry picked from commit 0e3d938968d05475861a01675c71701b6eff2b13)

editor/project_manager.cpp

@@ -436,7 +436,7 @@ private:
 		_test_path();
 
 		if (p_text == "")
-			set_message(TTR("It would be a good idea to name your project."), MESSAGE_WARNING);
+			set_message(TTR("It would be a good idea to name your project."), MESSAGE_ERROR);
 	}
 
 	void ok_pressed() {