element-web camelCase renaming (showLabsSettings -> show_labs_settings)

roles/custom/matrix-client-element/tasks/validate_config.yml

@@ -27,6 +27,15 @@
   with_items:
     - {'old': 'matrix_riot_web_.*', 'new': 'matrix_client_element_.*'}
 
+- name: (Deprecation) Catch and report renamed element-web settings
+  ansible.builtin.fail:
+    msg: >-
+      Your configuration contains a variable, which now has a different name.
+      Please change your configuration to rename the variable (`{{ item.old }}` -> `{{ item.new }}`).
+  when: "item.old in vars"
+  with_items:
+    - {'old': 'matrix_client_element_showLabsSettings', 'new': 'matrix_client_element_show_lab_settings'}
+
 - when: matrix_client_element_container_labels_traefik_enabled | bool
   block:
     - name: Fail if required matrix-client-element Traefik settings not defined