mozilla/pdf.js — pull request #847 by brendandahl (2011-11-29 19:40:33+00:00)
Title: Improved error handling

-Added an errorback to Page.startRendering.
-Added error box for the viewer.
-Handled more xhr errors.
-Handled initial pdf page errors.

Here are screenshots of the new error box:
http://people.mozilla.com/~bdahl/snps/pdfjs_error.png
http://people.mozilla.com/~bdahl/snps/pdfjs_error_open.png

Its not super pretty but I imagine it will some day get replaced with Julian's feedback feature.