Map distance app error when switching maps

[davidwilby]

Thanks for the awesome templates!

I'm finding that the map-distance app is erroring when switching maps on a local deployment (the gallery app is fine)

Python version 3.12 and 3.11 tried.

Environment tested

python 3.11.11 ❯ pip freeze anyio==4.8.0 appdirs==1.4.4 asgiref==3.8.1 asttokens==3.0.0 branca==0.8.1 certifi==2024.12.14 charset-normalizer==3.4.1 click==8.1.8 comm==0.2.2 decorator==5.1.1 executing==2.1.0 faicons==0.2.2 geographiclib==2.0 geopy==2.4.1 h11==0.14.0 htmltools==0.6.0 idna==3.10 ipyleaflet==0.19.2 ipython==8.31.0 ipywidgets==8.1.5 jedi==0.19.2 Jinja2==3.1.5 jupyter-leaflet==0.19.2 jupyter_core==5.7.2 jupyterlab_widgets==3.0.13 linkify-it-py==2.0.3 markdown-it-py==3.0.0 MarkupSafe==3.0.2 matplotlib-inline==0.1.7 mdit-py-plugins==0.4.2 mdurl==0.1.2 narwhals==1.21.1 orjson==3.10.14 packaging==24.2 parso==0.8.4 pexpect==4.9.0 platformdirs==4.3.6 prompt_toolkit==3.0.48 ptyprocess==0.7.0 pure_eval==0.2.3 Pygments==2.19.1 python-dateutil==2.9.0.post0 python-multipart==0.0.20 questionary==2.1.0 requests==2.32.3 shiny==1.2.1 shinywidgets==0.4.2 six==1.17.0 sniffio==1.3.1 stack-data==0.6.3 starlette==0.45.2 traitlets==5.14.3 traittypes==0.2.1 typing_extensions==4.12.2 uc-micro-py==1.0.3 urllib3==2.3.0 uvicorn==0.34.0 watchfiles==1.0.3 wcwidth==0.2.13 websockets==14.1 widgetsnbextension==4.0.13 xyzservices==2024.9.0

The following error is raised when choosing a different map from the dropdown, e.g. starting with WorldImagery and selecting Mapnik:

Traceback (most recent call last):
  File ".../lib/python3.11/site-packages/shiny/reactive/_reactives.py", line 584, in _run
    await self._fn()
  File ".../lib/python3.11/site-packages/shiny/_utils.py", line 279, in fn_async
    return fn(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^
  File "./map-distance/app.py", line 165, in _
    update_basemap(map.widget, input.basemap())
  File "./map-distance/app.py", line 185, in update_basemap
    map.remove(layer)
  File ".../lib/python3.11/site-packages/ipyleaflet/leaflet.py", line 3168, in remove
    if item.model_id not in self._layer_ids:
       ^^^^^^^^^^^^^
  File ".../lib/python3.11/site-packages/ipywidgets/widgets/widget.py", line 552, in model_id
    return self.comm.comm_id
           ^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'comm_id'
.../lib/python3.11/site-packages/shiny/reactive/_reactives.py:566: ReactiveWarning: Error in Effect: 'NoneType' object has no attribute 'comm_id'
  await self._run()
Unhandled error: 'NoneType' object has no attribute 'comm_id'

The app then freezes:

Also note that when a different map is selected and the page is refreshed, the new map loads correctly, e.g. Mapnik in this example:

[davidwilby]

This issue is caused in shinywidgets >0.4.0 but everything still works in 0.3.4. posit-dev/py-shinywidgets#174

[cpsievert]

Fixed by posit-dev/py-shinywidgets#179