On launching server (with our without plugins) it completes the start up with Done message and immediately crashes.

[09:38:46] [Server thread/INFO]: Done (19.003s)! For help, type "help"
[09:38:48] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.ReportedException: Ticking block entity

...

Caused by: java.lang.IllegalArgumentException: Cannot drop air

...

[09:38:48] [Server thread/ERROR]:     Cause of unexpected exception was
java.lang.IllegalArgumentException: Cannot drop air

Server then proceeds to shut down.

I do see lines that specify something about Hoppers, but I don't know if that's the actual issue.

at net.minecraft.world.level.block.entity.TileEntityHopper.a(TileEntityHopper.java:293) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3875-Spigot-17ca32d-5dfd33d]

Made a copy of the folders and ran the Vanilla 1.20.2 version and it didn't report a crash on start up.  However, I didn't enter the world to see if that would cause the issue.  Just wanted to test the startup conditions.  Issue could be in a non-loaded chunk for vanilla.

Log and crash log are attached.