scripts: west_commands: runners: Fix jlink is_ip

Commit f987e8c introduced a regression
where the is_ip check fails if no --id is passed as an argument.

Signed-off-by: Pieter De Gendt <[email protected]>

Author: pdgendt

scripts/west_commands/runners/jlink.py

@@ -30,6 +30,8 @@
 DEFAULT_JLINK_RTT_PORT = 19021
 
 def is_ip(ip):
+    if not ip:
+        return False
     try:
         ipaddress.ip_address(ip.split(':')[0])
     except ValueError: