Add check for empty extra_vars item

if in extra_vars a var that is a result of `generate_inventory..`
function is empty, skip the lso_interaction step altogether.

Kudos to KvK.

gso/utils/workflow_steps.py

@@ -93,6 +93,13 @@ def _update_sdp_single_pe(
         )["all"]["hosts"],
     }
 
+    if not extra_vars["pe_router_list"]:
+        return {
+            "playbook_name": "",
+            "inventory": {"all": {"hosts": {}}},
+            "extra_vars": {},
+        }
+
     return {
         "playbook_name": "update_pe_sdp_mesh.yaml",
         "inventory": {"all": {"hosts": {subscription["router"]["router_fqdn"]: None}}},
@@ -118,6 +125,13 @@ def _add_pe_mesh_to_pe(
         )["all"]["hosts"],
     }
 
+    if not extra_vars["pe_router_list"]:
+        return {
+            "playbook_name": "",
+            "inventory": {"all": {"hosts": {}}},
+            "extra_vars": {},
+        }
+
     return {
         "playbook_name": "update_ibgp_mesh.yaml",
         "inventory": {"all": {"hosts": {subscription["router"]["router_fqdn"]: None}}},
@@ -167,6 +181,13 @@ def _add_all_p_to_pe(
         )["all"]["hosts"],
     }
 
+    if not extra_vars["p_router_list"]:
+        return {
+            "playbook_name": "",
+            "inventory": {"all": {"hosts": {}}},
+            "extra_vars": {},
+        }
+
     return {
         "playbook_name": "update_ibgp_mesh.yaml",
         "inventory": {"all": {"hosts": {subscription["router"]["router_fqdn"]: None}}},