fix(python): raise for pl.concat(how="align") when no columns are shared between frames

[mcrumiller]

Resolves #13939.

[deanm0000]

Shouldn't it be maybe invalid operation error https://github.com/pola-rs/polars/blob/main/py-polars/polars/exceptions.py or maybe schema error

[mcrumiller]

Shouldn't it be maybe invalid operation error https://github.com/pola-rs/polars/blob/main/py-polars/polars/exceptions.py or maybe schema error

I think a SchemaError fits best. I'll set that for now and if someone else has a better reason for something else we can always switch. Thanks @deanm0000.

[alexander-beedie]

Hmm, we might need to tweak our exception docstrings a bit; I'd classify this as an InvalidOperation rather than SchemaError as there is nothing wrong with the schemas of the input objects; rather, it's the operation itself (trying to combine objects that don't share common columns) that's invalid 🤔 @stinodego, interested on your take here!

[ritchie46]

Must be InvalidOperation indeed. The inputs of the operations are not correct.

[mcrumiller]

@stinodego this failed due to the now-fixed pytest markers, can you rerun the tests for this to make the red X go away?

[stinodego]

@stinodego this failed due to the now-fixed pytest markers, can you rerun the tests for this to make the red X go away?

If you rebase the PR it should be fixed.