Mod Configs: Prevent Crash and Issue Error on Malformed ConfigSchema

[ItsEasyActually]

Currently the Mod Manager will crash if it runs into a malformed ConfigSchema.xml file.

It would be worth it to implement a system to catch that and throw an error for the user to view rather than crash the program.

Generally, this will end up just reporting to the user they messed up in their own mod, but it'd also allow users to report ConfigSchema.xml issues to authors of mods who may have shipped with malformed files.