For some reason plotly/package_data/widgetbundle.js is not being generated. I guess something goes wrong in the build script in js/package.json. Without the presence of that file, the global variable BaseFigureWidget._esm holds an invalid path, which leads to a somewhat surprising bug when using FigureWidget:

During import the function __getattr__ in graph_objects/__init__.py is being called and __init_subclass__ of AnyWidget is being invoked. Due to the missing file a FileNotFoundError is being raised (File not found: /usr/lib/python3.13/site-packages/plotly/package_data/widgetbundle.js).

inside __getattr__ there is a try block containing the import. I assume the intended usage of the try block is to catch any ImportErrors, since the except block will import a dummy-FigureWidget from missing_anywidget which just generates an error about a missing dependency.

However, the except block catches any exception, including the FileNotFoundError. This results in the user getting a misleading error message about a missing dependency (regardless whether that dependency is present or not). The actual fix would be to have the file plotly/package_data/widgetbundle.js present in the library.