mkdocstrings: Strange error

Getting this:

ERROR   -  Error reading page 'libraries/filehandlers/api.md': list index out of range 
Traceback (most recent call last):
  File "/workspace/.pip-modules/bin/mkdocs", line 8, in <module>
    sys.exit(cli())
  File "/workspace/.pip-modules/lib/python3.7/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/workspace/.pip-modules/lib/python3.7/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocs/__main__.py", line 134, in serve_command
    livereload=livereload
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocs/commands/serve.py", line 119, in serve
    config = builder()
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocs/commands/serve.py", line 114, in builder
    build(config, live_server=live_server, dirty=dirty)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocs/commands/build.py", line 274, in build
    _populate_page(file.page, config, files, dirty)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocs/commands/build.py", line 181, in _populate_page
    'page_content', page.content, page=page, config=config, files=files
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocs/plugins.py", line 94, in run_event
    result = method(item, **kwargs)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocstrings/plugin.py", line 138, in on_page_content
    modified_lines[i] = "\n".join(renderer.render(root_object, heading))
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocstrings/renderer.py", line 27, in render
    self.render_object(obj, heading_level, lines)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocstrings/renderer.py", line 59, in render_object
    self.render_categories(obj, heading_level + 1, lines)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocstrings/renderer.py", line 80, in render_categories
    self.render_object(method, heading_level + extra_level, lines)
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocstrings/renderer.py", line 50, in render_object
    lines.append(f'\n??? note "Show source code in {obj.relative_file_path}"')
  File "/workspace/.pip-modules/lib/python3.7/site-packages/mkdocstrings/documenter.py", line 190, in relative_file_path
    while path_parts[-1] != file_path_parts[-1]:
IndexError: list index out of range