Minor code corrections

quickemu

@@ -95,7 +95,7 @@ function get_port() {
     while true; do
         local CANDIDATE=$((PORT_START + (RANDOM % PORT_RANGE)))
         (echo "" >/dev/tcp/127.0.0.1/${CANDIDATE}) >/dev/null 2>&1
-        if [ $? -ne 0 ]; then
+        if [ ${?} -ne 0 ]; then
             echo "${CANDIDATE}"
             break
         fi
@@ -572,6 +572,7 @@ driver_iso=""
 disk_img=""
 disk="64G"
 usb_devices=()
+port_forwards=()
 ram=""
 cpu_cores=""