only add group if properly defined

also corrected skip message as this has to do with type, not name

fixes #40850

lib/ansible/plugins/inventory/yaml.py

@@ -112,9 +112,10 @@ class InventoryModule(BaseFileInventoryPlugin):
 
     def _parse_group(self, group, group_data):
 
-        self.inventory.add_group(group)
-
         if isinstance(group_data, MutableMapping):
+
+            self.inventory.add_group(group)
+
             # make sure they are dicts
             for section in ['vars', 'children', 'hosts']:
                 if section in group_data:
@@ -144,7 +145,7 @@ class InventoryModule(BaseFileInventoryPlugin):
                     self.display.warning('Skipping unexpected key (%s) in group (%s), only "vars", "children" and "hosts" are valid' % (key, group))
 
         else:
-            self.display.warning("Skipping '%s' as this is not a valid group name" % group)
+            self.display.warning("Skipping '%s' as this is not a valid group definition" % group)
 
     def _parse_host(self, host_pattern):
         '''
@@ -164,7 +165,7 @@ class InventoryModule(BaseFileInventoryPlugin):
 
         try:
             (pattern, port) = parse_address(hostpattern, allow_ranges=True)
-        except:
+        except Exception:
             # not a recognizable host pattern
             pattern = hostpattern
             port = None