try raising a built-in error rather than juniper ez class

inventory_provider/juniper.py

@@ -3,6 +3,7 @@ import re
 import ipaddress
 
 from jnpr.junos import Device
+from jnpr.junos import exception as EzErrors
 from lxml import etree
 import netifaces
 import requests
@@ -156,7 +157,10 @@ def _rpc(hostname, ssh):
         host=hostname,
         user=ssh['username'],
         ssh_private_key_file=ssh['private-key'])
-    dev.open()
+    try:
+        dev.open()
+    except EzErrors.ConnectError as e:
+        raise ConnectionError(str(e))
     return dev.rpc