1. WTF after closing?

closeSerial (/home/eddy/C-files/LibSidServo/serial.c, line 484): close fd

closeSerial (/home/eddy/C-files/LibSidServo/serial.c, line 489): Kill encoder thread

closeSerial (/home/eddy/C-files/LibSidServo/serial.c, line 491): close fd
*** bit out of range 0 - FD_SETSIZE on fd_set ***: terminated
Aborted