improve errorhandling in get_ntp

tools/get_ntp.py

@@ -6,5 +6,8 @@ c = ntplib.NTPClient()
 try:
     response = c.request(sys.argv[1])
     print(ctime(response.tx_time))
-except:
+except ntplib.NTPException as e:
-    print("ERROR")
+    print(f"ERROR during NTP request: {e}")
+    print("Usage: ntp-client.py <hostname>")
+    sys.exit(-1)
+