[Python-modules-team] Bug#875538: jupyter-nbextension-jupyter-js-widgets: fails to configure: json.decoder.JSONDecodeError

[Norbert Preining]

Package: jupyter-nbextension-jupyter-js-widgets
Version: 6.0.0-2
Severity: serious

Dear maintainer, 

the package consistently fails to configure with the following error:

Setting up jupyter-nbextension-jupyter-js-widgets (6.0.0-2) ...
/usr/lib/python3.5/runpy.py:125: RuntimeWarning: 'notebook.nbextensions' found in sys.modules after import of package 'notebook', but prior to execution of 'notebook.nbextensions'; this may result in unpredictable behaviour
  warn(RuntimeWarning(msg))
Enabling notebook extension jupyter-js-widgets/extension...
Traceback (most recent call last):
  File "/usr/lib/python3.5/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/lib/python3/dist-packages/notebook/nbextensions.py", line 1176, in <module>
    main()
  File "/usr/lib/python3/dist-packages/jupyter_core/application.py", line 267, in launch_instance
    return super(JupyterApp, cls).launch_instance(argv=argv, **kwargs)
  File "/usr/lib/python3/dist-packages/traitlets/config/application.py", line 658, in launch_instance
    app.start()
  File "/usr/lib/python3/dist-packages/notebook/nbextensions.py", line 961, in start
    super(NBExtensionApp, self).start()
  File "/usr/lib/python3/dist-packages/jupyter_core/application.py", line 256, in start
    self.subapp.start()
  File "/usr/lib/python3/dist-packages/notebook/nbextensions.py", line 871, in start
    self.toggle_nbextension(self.extra_args[0])
  File "/usr/lib/python3/dist-packages/notebook/nbextensions.py", line 861, in toggle_nbextension
    logger=self.log)
  File "/usr/lib/python3/dist-packages/notebook/nbextensions.py", line 407, in enable_nbextension
    logger=logger)
  File "/usr/lib/python3/dist-packages/notebook/nbextensions.py", line 345, in _set_nbextension_state
    cm.update(section, {"load_extensions": {require: state}})
  File "/usr/lib/python3/dist-packages/traitlets/config/manager.py", line 85, in update
    data = self.get(section_name)
  File "/usr/lib/python3/dist-packages/traitlets/config/manager.py", line 63, in get
    return json.load(f)
  File "/usr/lib/python3.5/json/__init__.py", line 268, in load
    parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
  File "/usr/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.5/json/decoder.py", line 357, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
dpkg: error processing package jupyter-nbextension-jupyter-js-widgets (--configure):
 subprocess installed post-installation script returned error exit status 1


Thanks

Norbert

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (200, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.12.0 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages jupyter-nbextension-jupyter-js-widgets depends on:
ii  python            2.7.13-2
ii  python-notebook   4.2.3-4
ii  python3           3.5.3-3
ii  python3-notebook  4.2.3-4

jupyter-nbextension-jupyter-js-widgets recommends no packages.

Versions of packages jupyter-nbextension-jupyter-js-widgets suggests:
iu  python-ipywidgets   6.0.0-2
iu  python3-ipywidgets  6.0.0-2

-- no debconf information