when-a-command-exits-non-zero

# Read the whole failure The first line of a failure is rarely the one that explains it. - Read to the end: the cause is usually below the summary, not above it. - A traceback's most useful frame is the last one inside your own package, not the deepest one overall. - Note the exact command and working directory before changing anything, so you can repeat the failure and know that you fixed it rather than moved it. Re-running unchanged to see whether it happens again is cheap, and it separates a real failure from a flaky one.