Your are probably right. I should fix that. My original idea was that people would stumble on it by accident and that it would feel fun. But if you don't it's not great. I also considered a cutscene discussing the safe but kind of forgot about it. Will add it. Thanks!
I mean, it did make me laugh that literally the first code I randomly tried worked. But I've played a lot of adventure games, and so have so many other people. It took me a good while before I decided to just try something. Though, I did also think for a moment, "...Is this thing broken and any 4 digits work?"