This is a submission for DEV's Summer Bug Smash: Smash Stories powered by Sentry . Two bugs, one story. A parser that failed on every real call, plus the test that certified it as working for two review rounds. The second one is the one worth reading about. What the code does I was writing adapters for a protocol indexer. Each adapter has a Receipt parser: it receives the on-chain state changes from one transaction and produces a structured outcome, "this account swapped...