I created the same bug report on the Physics mod Github, but I can't be sure it's them given the context of the error. Breaking an empty 32-stack storage drawer with the physics mod installed causes a client crash with the error:

Error: java.lang.NullPointerException: Cannot read field "itemStackEntity" because the return value of "net.diebuddies.physics.PhysicsMod.getCurrentInstance()" is null
Exit Code: -1

Storage Drawers: StorageDrawers-1.18.2-10.2.1.jar
Physics Mod: physics-mod-2.7.6-mc-1.18.2-forge.jar
Forge: forge-1.18.2-40.1.47

Crash Report : https://pastebin.com/bmHSaUkE

I was playing on a modded server of mine and it does not look like the server was impacted, only the client.

FWIW, I can confirm it happens if you break a mostly full 2x2 storage drawer, also.