fix: handle undefined theme cookie name for lms settingss

Author: hinakhadim

tutorindigo/plugin.py

@@ -196,13 +196,17 @@ def _override_openedx_docker_image(
     if filename in PIPELINE['JAVASCRIPT']:
         PIPELINE['JAVASCRIPT'][filename]['source_filenames'] += dark_theme_filepath
 
+{% if INDIGO_THEME_COOKIE_NAME %}
 MFE_CONFIG['THEME_COOKIE_NAME'] = '{{ INDIGO_THEME_COOKIE_NAME }}'
+{% endif %}
 """,
         ),
         (
             "openedx-lms-production-settings",
             """
+{% if INDIGO_THEME_COOKIE_NAME %}
 MFE_CONFIG['THEME_COOKIE_NAME'] = '{{ INDIGO_THEME_COOKIE_NAME }}'
+{% endif %}
 """,
         ),
     ]