Die on key mismap and stop throwing errors.

[Zemurin]

if you load a file with eu4 but you accidentally set "eu3" as source key, you will get several tens of thousands of error popups, one per line. This is really not good.

[Idhrendur]

And maybe record the other settings when you do that so you don't have to hunt down the paths again.

That result may be because I hard close the tools as soon as I see one of those errors.