Errors with and without error-type

Some xforms-*-error events have an error-type, and many don't. 


Those with:



xforms-action-error 
<https://www.w3.org/community/xformsusers/wiki/XForms_2.0#evt-actionError>
xforms-binding-error (sometimes)
xforms-submit-error 
<https://www.w3.org/community/xformsusers/wiki/XForms_2.0#submit-evt-submit-error>

xforms-action-warning


Often we say that an xforms-binding-error is dispatched, without saying 
what the error type is.


We should discuss this.


Steven