Output widget does not show in Jupyterlab

[dionhaefner]

In Jupyterlab,

import ipywidgets as widgets
widgets.Output()

gives

Error displaying widget

and writes the following to the console:

Could not instantiate widget           manager-base.js:272
Error: Could not create a model.
Stack trace:
xj6n/t.reject/<@<snip>/lab/static/main.3da2a829f205f34a09fd.js:1:1483118           utils.js:119
Error displaying widget           renderer.js:84
Module @jupyter-widgets/output, semver range 1.1.0 is not registered as a widget module           renderer.js:85
Error: Object 'jupyter.widget' not found in registry           default.js:1443
uncaught exception: Module @jupyter-widgets/output, semver range 1.1.0 is not registered as a widget module
Error: Object 'jupyter.widget' not found in registry

All other widgets I have tried work just fine.

pip show jupyterlab ipywidgets:

Name: jupyterlab
Version: 0.31.1
Summary: The JupyterLab notebook server extension.
Home-page: http://jupyter.org
Author: Jupyter Development Team
Author-email: jupyter@googlegroups.com
License: BSD
Location: /opt/conda/lib/python3.6/site-packages
Requires: notebook, jupyterlab-launcher, ipython-genutils
---
Name: ipywidgets
Version: 7.1.0
Summary: IPython HTML widgets for Jupyter
Home-page: http://ipython.org
Author: IPython Development Team
Author-email: ipython-dev@scipy.org
License: BSD
Location: /opt/conda/lib/python3.6/site-packages
Requires: ipython, nbformat, ipykernel, traitlets, widgetsnbextension

[dionhaefner]

Maybe related:

During installation, I get

[4/4] Building fresh packages...
warning Error running install script for optional dependency: "/opt/conda/share/jupyter/lab/staging/node_modules/canvas: Command failed.\nExit code: 1\nComm$info This module is OPTIONAL, you can safely ignore this error

[tnystrand-altiscale]

I have the same issues in lab. Everything works in notebook.

In addition slider and most third packages like sparkmagic don't work for me either. Exact same set up, exact same error. Did manage to install canvas when npm was not installed while in a conda environment, but the lab issue persisted.