Confusing build error from notebook code error

[matthew-brett]

A code error in a notebook gives the following to-me confusing error jupyter-book build:

Executing: bad_notebook in: /Users/mb312/dev_trees/minjb                                                                           
WARNING: Found a content page that is not in _toc.yml: bad_notebook.ipynb.
WARNING: Execution Failed with traceback saved in /Users/mb312/dev_trees/minjb/_build/html/reports/bad_notebook.log

Exception occurred:
  File "/Users/mb312/Library/Python/3.8/lib/python/site-packages/ipython_genutils/ipstruct.py", line 134, in __getattr__
    raise AttributeError(key)
AttributeError: language_info

It's true that the initial message gives execution failed, and that I can find the error in the given .log file, but it wasn't clear to me until I spent some time tracking down that this meant literally that there was a code error in the notebook; it looked like the 'execution' that had failed was the notebook building phase, with that puzzling 'language_info' error.

Is there any way of making that error more informative, so others don't get confused in the same way?

I've put up a minimal reproducer repo / branch at https://github.com/matthew-brett/minjb/tree/bad-notebook-error

git clone https://github.com/matthew-brett/minjb -b bad-notebook-error
cd minjb
make

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