Nine sites across five specs do `collection.find(...)` and dereference the result immediately. When the row is missing the test dies with "Cannot read properties of undefined" naming a line of test plumbing, which says nothing about what was expected — and that is exactly how favorites-filter:169 failed without producing a usable signal.
The message names what was wanted and how many rows were searched. That distinction carries real diagnostic weight: "0 rows" means the fixture never landed, "37 rows" means it landed and the predicate is wrong, and those are different bugs to chase.
It lives in its own module importing nothing, rather than in support/api.ts. That file imports @playwright/test, and vitest.config.ts runs tests/unit with environment: 'node' — putting six lines of pure logic there would drag a browser harness into the unit suite to test them. api.ts re-exports it so specs still reach it through fixtures.
Throws rather than returning null, because every caller wants the row: an error at the point of the miss beats a null threaded through three more lines before something unrelated fails.
Frontend: 30 unit tests pass, lint unchanged at 2 pre-existing warnings, build clean.
Ref #241
