And it looks like moving the stream library to a path that contains less characters fixes it.

Try moving your steam library from under \program files (x86)\etc etc

REMEMBER to update your config.xml to the new DATA directory location.

It seems once you get a path that is too long in characters it causes the exception and crash.
It may have a lot to do with the format of the GM module naming convention of using a long unique character set... in this case "ModuleName_48678138-d3d8-41db-80f7-a49c254af959"


<attribute id="Module" value="48678138-d3d8-41db-80f7-a49c254af959" type="23" />
<attribute id="Name" value="HellsKeep" type="23" />
<attribute id="Type" value="Add-on" type="23" />
<attribute id="UUID" value="8f641562-e5ca-4a51-ae20-3ee471013f0a" type="23" />