check supported file extensions before upload
I <a href="https://writelatex.uservoice.com/forums/137318-feedback/suggestions/6280041-tiff-support">experiences some problems with file upload</a>. Instead of after upload, how about an up-front warning for unsupported file extensions, plus as link to the <a href="https://www.writelatex.com/help/1-what-file-types-do-you-support">list of supported ones</a>?
Thanks for the feedback — better file upload support is definitely planned, and filtering on extension before upload will be a part of that work. :)