What breaks
A honk scans blocks around the vehicle. The scan skips anything below y 0 and never checks the top of the world, so a honk at the top reads past the chunk and the event never finishes.
Honks stay in range
Server only
Fixes a vanilla bug where honking a vehicle near the top of the world makes the server throw the same error every tick.
Honking at a trader still opens the doors, the same as vanilla.

A honk scans blocks around the vehicle. The scan skips anything below y 0 and never checks the top of the world, so a honk at the top reads past the chunk and the event never finishes.
The scan is trimmed to the world height before it runs. A block-scan event that still reads out of range is ended. That covers every block-scan game event, not only the honk.