- Relocate LED turn-off to i1pro_close_port() before closing communication port
- Guard LED turn-off and log updates against NULL pointers and closed ports in del_i1proimp()
- Ensure clean termination, unblock, and joining of i1pro switch and trigger threads in both i1pro_close_port() and del_i1proimp()
- Protect against NULL terminate callback on Unix/macOS