as for the access violation, it might be the version advancemap you're using. If you're using AdvanceMap 1.95, try switching to AdvanceMap 1.92. That or you might have accidentally broken something. Try restarting the program in this case. Sometimes there are things we do that can corrupt the file, which is why you should always have a backup file and just like a game, save often to your backup just in case you hit a wall.
I'm using the version 1.92 of Advance Map and yes, by restarting the program it goes back to how it was originally. The problem is inserting the tileset into the Emerald ROM. I didn't touch the width at all but I made the height just a little bit longer because I need space to insert a few new trees. But exactly when I insert it, I get that error.
Edit: Ok everything didn't crash now the only thing that did pop up was something about the dib being invalid.