Report the name of an invalid ARIA Role

[clapierre]

It would have been nice to know which role was in error.
In this case the role was "decorative" instead of "presentation"

but it took a bit of detective work to find out that, would have been nice to have that called out in the report where it said invalid aria role (why not just say what it found)

[marisademeglio]

When #82 is done, I think it will help here by showing the existing role attribute values.

Generally speaking, we can't say what role you meant to use instead.