TOC eats up code cells

[maalaria]

Dear all,
I am encountering an issue when using the TOC extension. When it is installed some of the code cells in the notebook disappear. When uninstalling TOC and restarting the notebook they reappear.
I am using Jupyterlab version 2.2.9.
Attached you find two images illustrating the issue.
ps. I didn't read through all the issues reported, please excuse if this is a doublet.

with TOC installed

without TOC

[Jacobzhangjw]

@maalaria
Hi, I found the answer in #135 will fix this issue.