Knights & Knaves Alehouse

There is a line in this spell's description that can be read two ways, and I'm trying to figure out what is intended.

If a fire trap is cast after a wizard lock, the former is negated, . . .

By "former" does it mean the first of the two spells mentioned in this line (fire trap) or the first of the two spells cast (wizard lock)?

The literal wording says the fire trap is negated, but I think the wizard lock being negated is what was intended (because that makes sense, and the other way around doesn't).

I don't know, I think it makes sense to trap the door and then lock it.
A knock spell would unlock it unleashing the trap.

I think the spirit of it is that the wizard lock is negated.