BossBar related crash on botania:

[Polarite]

https://mclo.gs/7xWjVkH
Crash upon entering a server.
Linux client and server.

[brunoxkk0]

I've been looking at the crash report and didn't see any reference to NecroTempus.
The mod pointed out in the crash is Botanical Addons. Please check this mod and see if it solves the problem.