Propagate Plotly.js console errors to Python

[ndrezn]

Occasionally Plotly.js console errors are relevant to Python developers, for example in: plotly/plotly.js#7289 where we show an error about a missing style.

For Python developers (especially in Jupyter) this is really gnarly to debug because they're never shown the issue unless they can figure out to check the console somehow.

I would wager there are a class of JS errors that we might not catch like this but I might be wrong. @alexcjohnson do you know if we have any handling in place for this kind of thing already?

[alexcjohnson]

I’m not sure we want to go down this road. Most JS errors are simply bugs, those few where we’re trying to give the user some info shouldn’t we be able to handle before it leaves Python?

The other one is to expose Plotly.validate to Python users, that’s able to catch more than Python-side validation because it happens after supplyDefaults so it can tell you about interactions between different attributes (only reference axes that exist, only set marker attributes if you’re showing markers, that sort of thing). Do we already have an issue for that?