quantcpp serve crashes with SIGABRT on port conflict instead of graceful error

[unamedkr]

Description

When the requested port is already in use, quantcpp serve crashes with SIGABRT (exit code -6) instead of showing a user-friendly error message.

Steps to Reproduce

# Start first server
quantcpp serve smollm2:135m --port 8080 &

# Start second on same port
quantcpp serve smollm2:135m --port 8080
# → Process crashes with SIGABRT, no error message

Expected

Error: port 8080 is already in use. Try a different port with --port.

Environment

• quantcpp 0.12.1 (PyPI), macOS 15

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Reported by ClawTeam Claw-1 (Quickstart persona) — Round 2

[unamedkr]

Fixed in PR #76 (merged to main). Port conflict now shows friendly error instead of SIGABRT.