The schema has ON DELETE SET NULL on cables.from_port_id /
cables.to_port_id, but the cables CHECK constraint requires exactly one
of (port/device/io) to be non-null per side. Setting both refs to NULL
on a port-delete violates the CHECK, blowing up the DELETE with a 500.
DeletePort now opens a tx, deletes any cable that referenced the port
on either side, then deletes the port. Same observable effect from m's
POV: cables that point at a deleted port are gone (he can re-draw with
the manual cable tool if he still wants them).
mAi
f9c245fbcc