Apparently you tried to place a block 1 block above the height limit.
There are two hard things in programming: cache invalidation, naming things, and off-by-one errors.
Looks like three things to me.
Hopefully fixed in the next update
That’s the joke ;).
As @5tingr4y said, the issue appears to be that the lightning bolt is being spawned one block above the max height. Was it spawned in by a command, or did it occur naturally?
This happend naturally.
What forge mods do you have installed?
All are listed in the crash report.
Do you know if Pixelmon, or any of the Pixelmon-related mods you’ve installed, does any kind of lightning bolt spawning?
I believe it does not.
This happend again:
After the server crashed, I went to the world it happend in and saw it was thunderstorming.
Edit: The player who crashed it said it was raining right before it crashed
Crash fixed, a new version of SpongeForge will be available shortly