docker_node: labels operation fails when parameter 'labels' is None (#52662)

* docker_node: Fix for situation where labels parameter is None

* docker_node: Fix for situation where labels parameter is None and labels are not removed

lib/ansible/modules/cloud/docker/docker_node.py

@@ -229,6 +229,7 @@ class SwarmNodeManager(DockerBaseClass):
 
             if self.parameters.labels_to_remove is not None:
                 for key in self.parameters.labels_to_remove:
+                    if self.parameters.labels is not None:
                         if not self.parameters.labels.get(key):
                             if node_spec['Labels'].get(key):
                                 node_spec['Labels'].pop(key)
@@ -238,6 +239,10 @@ class SwarmNodeManager(DockerBaseClass):
                                 "Label '%s' listed both in 'labels' and 'labels_to_remove'. "
                                 "Keeping the assigned label value."
                                 % to_native(key))
+                    else:
+                        if node_spec['Labels'].get(key):
+                            node_spec['Labels'].pop(key)
+                            changed = True
 
         if changed is True:
             if not self.check_mode: