Macro Rendering Error

TypeError: 'DebugUndefined' object cannot be interpreted as an integer

Traceback (most recent call last):
  File "/home/andreas/src/env-3.10/lib/python3.10/site-packages/mkdocs_macros/plugin.py", line 480, in render
    return md_template.render(**page_variables)
  File "/home/andreas/src/env-3.10/lib/python3.10/site-packages/jinja2/environment.py", line 1291, in render
    self.environment.handle_exception()
  File "/home/andreas/src/env-3.10/lib/python3.10/site-packages/jinja2/environment.py", line 925, in handle_exception
    raise rewrite_traceback_stack(source=source)
  File "<template>", line 36, in top-level template code
TypeError: 'DebugUndefined' object cannot be interpreted as an integer