This had happened to me before, this kind of error mostly happens due to a bad either npc file, shader file, or bot file.
In either of those files, JA uses { and } to show different things, and when using it incorrectly, then that will happen. To fix this, check all your new .pk3 files that you have put in and check all the files that use { and } and make sure that for each "{" you find a "}". So basically make sure that you have the same number of { as }.
There once was a member of this land,
A humerous posting he had planned.
But when he posted,
By mods he was toasted,
And he had found himself banned.
