This link contains the crash report...

https://pastebin.com/u5NZeRAW

I'm sorry it's a slightly older version but, I just wanted to let you be aware...

The URL you posted is broken.

This is caused by some mod returning an Immutable list in the getSpawnableList method in custom biomes. Go through your recently updated mods and figure out which one causes the crash, and report it to them. This is not Ender Zoo's fault.

Sorry for the super late reply, but I can't seem to figure out what mod is causing the crash... Is anyone able to figure this out?... I really appreciate the assistance.