Investigate changing error summary heading to improve screenreader usability

[danielnissenbaum]

Error summary component

The error summary currently has the heading:

There is a problem

Followed by a list of links to the fields where there are errors.

My hypothesis is that usability would be improved for screenreader users but also everyone, if the heading was more explicit and said:

There's a problem with these sections on the page

Creating this ticket to set up a test for this hypothesis and depending on results, update the component.