Submitting using an sl-button includes an empty name-value pair

[benopotamus]

See the result of using the sl-button submit button in shoelace-test.html. Unlike the native HTML button, the sl-button includes '': [''] in the request.

e.g.

{'': [''],
 'field-in-fieldset-a': [''],
 'mycolorpicker': [''],
 'myinput': [''],
 'myradiogroup-preselect': ['1'],
 'myrange': ['0'],
 'myrating': ['0'],
 'mytextarea': [''],
 'shoelace-select': ['']}

[benopotamus]

The '': [''] is actually the name and value of the sl-button used to submit the form.