When no simulator is booted, grep -oE finds no UUID and exits 1. With
set -euo pipefail, that non-zero exit propagates through the command
substitution and kills the script at the UDID= assignment before it can
fall through to the boot-one branch.
Fix: add || true to both find_sim and sim_name pipelines so they always
return 0 regardless of whether a match was found.
Also replace sleep 2 with xcrun simctl bootstatus <UDID> -b, which blocks
until the simulator is fully booted — more reliable than a fixed delay
and faster when the simulator starts quickly.
Update docs/building.md §9 to show the bootstatus command.
Talon
e2616b60b4