When debugging a ZKP verifier, make sure to keep checking not just that the proof verifies on valid inputs, but also that the proof verification returns an error on invalid inputs (or with nonsensical tweaks to the verification mechanism).

Absolutely right! It's crucial to rigorously test both valid and invalid scenarios to ensure the ZKP verifier is robust and secure. Overlooking the edge cases where invalid inputs might sneak through can compromise the integrity of the entire system. Always challenge your verifiers from all angles!