Improve error message

[anoukvlug]

This PR addresses issue #1555, by improving the error message that is being raised for the following error ModuleNotFoundError: No module named 'shapely.io'.

[TimoRoth]

Is the new notebook part of this PR intentionally?
Also, the text of the error message can change depending on the python version. And maybe even system language?
Much better to check the name property of the exception instead.

[anoukvlug]

Yes, that does make sense. However I don't think I fully understand you suggestion. What do you mean with name property?

Thanks for noticing the notebook, that was not supposed to be included in this PR.

[TimoRoth]

ModuleNotFoundError inherits the name property from the ImportError Exception class.
So you can just get the module that wasn't found from the name property:
if err.name == "shapely.io":

You'll also most definitely want to add an else-Branch to that if that re-raises the exception, otherwise this could hide other errors and continue despite the loading having failed.

[anoukvlug]

Thanks for the explanation @TimoRoth! Is the latest commit what you had in mind?

[TimoRoth]

To re-raise an exception, just call raise without any arguments. Otherwise you might obscure where the error actually came from.

One more issue I could see is that by creating a new ModuleNotFoundError without the name/path argument set, you might be breaking conventions.

What you could do instead:

                if err.name == "shapely.io":
                    err.msg = "You need shapely version 2.0 or higher for this to work."
                raise

[anoukvlug]

Thanks for the coding lesson. That looks indeed better :)

[fmaussion]

Thanks!