Attempting to convert a notebook with pasted image to PDF fails with an error

[andrii-i]

Attempting to convert a notebook with pasted image to PDF fails with an error in both Jupyterlab and Notebook head-of-master.

Reproduce

1. Create a notebook.
2. Copy an image and paste it into the markdown cell.
3. Attempt File->Save and Export Notebook As ...->PDF

• Created based on Using nbconvert from ipynb to pdf fails when there is an image that has been pasted in the notebook on Ubuntu using xelatex. jupyterlab/jupyterlab#14365 by @frohro

[tuncbkose]

As far as I can tell, the problem is that the pasted image is stored directly in the notebook, base64 encoded (according to this).

It shouldn't be too difficult for nbconvert to look for these attachments and convert them into files in the same directory, so that outputs like markdown and latex will work properly.