JupyterLab: Failed to load model class 'AnyModel' from module 'anywidget'

[Kreijstal]

Describe the bug

installed anywidget using
pip install "anywidget[dev]"
Then went ahead and tried to counter example:

import anywidget
import traitlets

class CounterWidget(anywidget.AnyWidget):
    # Widget front-end JavaScript code
    _esm = """
    function render({ model, el }) {
      let button = document.createElement("button");
      button.innerHTML = `count is ${model.get("value")}`;
      button.addEventListener("click", () => {
        model.set("value", model.get("value") + 1);
        model.save_changes();
      });
      model.on("change:value", () => {
        button.innerHTML = `count is ${model.get("value")}`;
      });
      el.appendChild(button);
    }
    export default { render };
    """
    # Stateful property that can be accessed by JavaScript & Python
    value = traitlets.Int(0).tag(sync=True)

Reproduction

Since in the documentation it wasn't shared how to use it I assumed it was like this

counter=CounterWidget()
counter

Logs

[Open Browser Console for more detailed log - Double click to close this message]
Failed to load model class 'AnyModel' from module 'anywidget'
loadClass@http://127.0.0.1:8888/lab/extensions/@jupyter-widgets/jupyterlab-manager/static/134.a63a8d293fb35a52dc25.js?v=a63a8d293fb35a52dc25:1:74936
loadModelClass@http://127.0.0.1:8888/lab/extensions/@jupyter-widgets/jupyterlab-ma

In dev tools:

Error: No version of module anywidget is registered

System Info

$ npx envinfo --system --browsers
(node:19624) ExperimentalWarning: CommonJS module C:\Users\kreij\scoop\apps\msys2\2022-01-28\mingw64\lib\node_modules\npm\node_modules\debug\src\node.js is loading ES Module C:\Users\kreij\scoop\apps\msys2\2022-01-28\mingw64\lib\node_modules\npm\node_modules\supports-color\index.js using require().
Support for loading ES Module in require() is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
Need to install the following packages:
envinfo@7.14.0
Ok to proceed? (y) y


  System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 Intel(R) Core(TM) i7-1065G7 CPU @ 1.30GHz
    Memory: 3.42 GB / 15.79 GB
  Browsers:
    Edge: Chromium (127.0.2651.74), ChromiumDev (127.0.2610.3)
    Internet Explorer: 11.0.19041.4355

npx envinfo totally ignored the fact that I only use firefox, hilarious.

$ pip freeze | grep -E "anywidget|jupyter|notebook"
anywidget==0.9.13
jupyter-cache==1.0.0
jupyter-events==0.10.0
jupyter-lsp==2.2.5
jupyter_client==8.6.3
jupyter_core==5.7.2
jupyter_server==2.14.2
jupyter_server_terminals==0.5.3
jupyterlab==4.2.5
jupyterlab_pygments==0.3.0
jupyterlab_server==2.27.3
notebook_shim==0.2.4

Severity

blocking all usage of anywidget

[Kreijstal]

Solved it, not sure if it's by restarting the system or because I patched cpython
msys2-contrib/cpython-mingw#183