One thing I've noticed is that if I have a syntax error in my JAS json configs… the settings don't load properly (obviously)… and the console output indicates that there is a problem (as it should)… but then what also happens is that other mods config files get corrupted and are incomplete (almost like they were open and partially written to).

Two mods I've noticed that are severely affected are Enviromine and ForgeEssentials. The Enviromine configs get borked, and the FE data in the world folder disappears.

Long term I'm not opposed to looking at how JAS could crash the game in a more friendly manner.

There is also the issue of, if not crashing immediately on world load error being detected, that the world is generating without JAS and chunk spawns would not occur.

Short term, I recommended backing up config files.