False GM1041 Error: 'Undefined' Instead of 'Real'

Hello everyone, I have a recurring issue that is really bothering me because it keeps happening: I'm talking about the false error 'GM1041 The type 'Undefined' appears where the type 'Real' is expected.' This gets flagged every time i test the project , even though the variables have been correctly declared as real, for example here: save_game(global.current_file_id);

I've tried setting the variable (in both the Game Start and Create events of the first...

False GM1041 Error: 'Undefined' Instead of 'Real'