latex error not shown with %matplotlib notebook

[mfittere]

Hello,

In case of an error in a latex formula,e.g.
plt.ylabel(r'$\thet$') # as \thet is not known as a command
no error is reported instead the notebook switches constantly to mode "busy" and back. This only occurs with
%matplotlib notebook
Instead with
%matplotlib inline
the following error message is shown:

ValueError:
\thet
^
Unknown symbol: \thet (at char 0), (line:1, col:1)

Is it possible to also post the error message in interactive mode, explicitly with %matplotlib notebook?

[takluyver]

Pinging @tacaswell

[tacaswell]

I have a good guess as to what is going wrong and it is due to the auto-redraw on stale logic.

post-execute event checks if any figures are stale -> figure is stale -> triggers redraw -> redraw fails -> the figure is still stale -> post-execute event checks if any figures are stale -> ...

[takluyver]

So that would be a mpl issue? Feel free to use this thread to work out the details, and let us know if we can do anything on our side.

[tacaswell]

What are the conditions when 'post_execute' hook is called?

Fixing the infinite loop is relatively strait forward (just mark the figure as not stale, even if drawing failed), but I am not fully convinced correct.

Getting the exception to propagate across is going to be more difficult an the draw is run via a callback from the js side via a comm we have set up (this is the same reason of the other issues where tracebacks and print calls from mouse / keyboard events do not make it back out to the notebook. These issues should be addressed by ipympl.