Conflicting mods:
Durability Viewer 1.21-1.11.0
ImmediatelyFast 1.6.5+1.21.1

Log: https://mclo.gs/AzULbE0

Likely that Durability Viewer thought equipped was null because a class method was changed.

This is very likely not related to ImmediatelyFast. If you think ImmediatelyFast is actually at fault, try reproducing the issue with only those two mods installed and then upload the log again, as well as detailed steps so I can reproduce the issue on my end.

Oops, forgot to test that. I shall try that. The steps would be hard to replicate since it seems to be random.