24a52a5bae
- Background subshell '( cmd ) &' + 'wait' interacted badly with set -euo pipefail on macOS bash 3.2, killing the script silently before the progress-bar's error branch could run - New approach: just 'cmd &' (no subshell), bracket the whole bg+wait region with 'set +e' / 'set -e', then check rc explicitly - Also adds ERR-trap with call stack + RUN_QUIET_DEBUG=1 fallback (streams output directly via tee, useful for debugging build failures)
