Output and exit codes: Where output goes

• A report goes to stdout.
• A refusal, and anything with no report at all, goes to stderr — so redirecting stdout leaves an empty file rather than a file whose contents are the reason there is no report.
• Under --json, everything is in the one envelope on stdout.
• A canceled scan that gathered something still has a report, and that goes to stdout like any other.

sqlmc list coverage --list "All Prod" --json > coverage.json
# coverage.json holds the envelope; nothing else is written to it