navidrome's install died on 2026-08-01 and left no explanation: the log
had only "Started container for navidrome (exit 1, up_app.sh:130)". The
compose output was captured into `result` and never read, and stderr was
not captured at all — so the one thing that says WHY (image pull EOF,
port clash, missing external network) was thrown away at the moment it
mattered.
Capture stderr and print the tail of the output on failure, before
checkSuccess (which can exit). Both the rootless and rooted call sites.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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