https://pastebin.com/RUUzFCF0
I thought the void isn't solid, get it? (Bad joke)
I have no idea what the crash log said all about, but I saw some better end show up in there, so I'll start from here then.

I'll try after me home, but last time, me was changing dimension to the end, it doesn't seem to crash until it load up a few chunks or try to generate something at somepoint, and then crash.
PS. Removing the mod still crash and I got this one instead. https://pastebin.com/1vnFcDJR - Now I see Abnormal Core and Optifine... Hm..

I genuinely have no idea what could be the cause of this error, except that it doesn't seem to come from BetterEnd. You best bet is to remove mods one by one until you find the culprit (or use binary search)..remember to also remove Optifine..sometimes it is the cause of many subtle issues, even if i do not really think this is the case

Found it, Kingdom Keys may have messed something in the end settings. Thanks for the time. :3

Bad joke :P This error doesn't seem to come from BetterEnd at all, but there is a pretty reliable way to know for sure...try removing BetterEnd and see if it still happens. Also if you could provide me with some more context it would be of help, like for example: what you were doing in-game when the crash happened, what happened around you, the last action you did etc...