Displaying "Merge successful" message in two cases when it wasn't

[aaronfreed]

1. It writes an empty map file (most commonly, the user dragged the wrong folder onto the app). If it writes an empty map file, then by definition, the merge was not successful!
2. It fails to write the map resources folder (which, to my knowledge, happens when overwriting an old map file that is in use on Windows).

While it could be argued that either of these falls under user error, without any sort of warning, users have no way of knowing this. Moreover, while I know that both of these are problems, I still frequently fail to notice that I've done them. Atque should warn about them both.