jupterlab-extionsion fails due to HTTP Error 500

[hzfmer]

Describe the bug
A clear and concise description of what the bug is.
Once I install this extension, the jupyterlab manager doesn't work:

The problem disappears when the ext is uninstalled.

To Reproduce
Steps to reproduce the behavior:

1. Install nbgather by jupyter labextension install nbgather

Screenshots
Seen above

Desktop (please complete the following information):

• OS: Red Hat Enterprise Linux Server release 7.6
• Browser: Chrome
• Version [e.g. 22]

** Jupyter
jupyter core : 4.5.0
jupyter-notebook : 6.0.0
qtconsole : not installed
ipython : 7.6.1
ipykernel : 5.1.1
jupyter client : 5.3.1
jupyter lab : 1.0.2
nbconvert : 5.5.0
ipywidgets : 7.5.0
nbformat : 4.4.0
traitlets : 4.3.2

Additional context
I recalled to see this buggy behavior on another extension, "autoversion". Didn't test it.

[andrewhead]

Roger! Thanks for the tip-off and the detailed report 👍 I'll look into this shortly.

[junqilu]

Also got this error

[andrewhead]

Thanks @junqi95 . What version of jupyter lab are you using?

[junqilu]

Thanks @junqi95 . What version of jupyter lab are you using?

I'm using version 1.1.4.