[RMXP] Use item on game environment

Hey!

I've started working on an adventure game project, using RPG Maker XP. The game system would require the following to be possible: When the player thinks he's encountered an element of the environment he can interact with, he should be able to go in its inventory and try to use an item - if that's what he's supposed to do, it works ; it it isn't, he's just told it won't do. Nothing more than that.

Basically, using the Red Key on the Red Door will unlock it ; but using the Banana Peel on the unrelated Traffic Light, on a non-interactive part of the environment or in thin air will just trigger a "you can't do that" bit of text. Pretty much what's used in the Pokémon series, among others.

Now, I searched it up, and found this. Good news: It looks exactly like what I need. Bad news: It barely works. It crashes when I'm in a "you can't do that" situation - and the more I try to fix, the worse it gets. I tried making the changes to the code as mentioned in the referenced thread, but it doesn't seem to do any good.

I searched for another similar script, but it seems like it's the only one that would allow me to pull that of. So, I'm kind of stuck, and this is why I made this thread. Could someone please help me making this work? That would be greatly appreciated.

Thanks!