Server crash, multiple times

A while ago, I was playing with a friend on a modded server with a custom modpack. Suddenly, when night came, the server closed itself. We restarted it, and the server closed again ONLY after one of us logged in. We looked into it and the crash report said it was because of a ticking entity error (I later found out it was a zombie). We fixed it by setting the difficulty on peaceful, but after a while, it happened again. And it keeps happening every now and then even after several days, even though it usually fixes itself. I'd like to know what the cause is, if you could help me figure that out. Thanks!

Here's the log https://pastebin.com/PGi5y66M

Here's the list of mods

But it happened to me in singleplayer as well, using the same modpack. And again, it doesn't happen everytime, I just finished a 1 hour session and nothing went wrong, even during the in game nights. Is there really nothing that could be done to prevent this?

Quote from Roman

On the same world?

No, but since it happened in singleplayer on a different world, I would assume it's not related to the world itself, but to something in the modpack (mods conflicting perhaps)