[FileAPI] Question on order of calling onerror vs. setting error attribute

[I tacked this on to another question but should have asked it separately, so here it is.]

In the File API spec, section 8.5.6, step 1 starts "Fire a progress event called error. Set the error attribute;". Doesn't firing an event call the event handler immediately (synchronously)? I followed through the links and references and it seems to, although I could have easily missed something. If it does, this seems to be saying to call the error handler *before* setting the error attribute, which seems backwards.

Thanks,
Brian