type="url" validation error is not shown on firefox

[mhl]

On the document upload page, like: /upload_document/upload/election/2010/post/65937/, say, we've seen on two different Firefox browsers that if you don't put a URL in the source URL field, you don't get any client-side error due to the type="url" attribute of the input field. This means you can't submit the form to upload the document, but it's totally unclear why not!

We've seen this on two different people's laptops running the Linux version of Firefox 53.0

[jf1]

I've always thought it strange that users are expected to download, save, upload and provide a link when they should be able to just provide a link that the site can then wget.

The suggestion to amend the photo upload page is in DemocracyClub/yournextrepresentative#150

[mhl]

@jf1 I'm afraid that your comment here is only very loosely related to this issue, which is specifically about a client-side form validation error not appearing on particular browsers. This comment and the link you've made to another ticket (which is unrelated to this issue) unfortunately create notification noise, and confuse people looking at both tickets since they have to work out if they're missing some relevance. I really value your insights into how the usability of the site can be improved, but please try to keep each comment focused on the actual issue, so it's as clear as possible for people working on fixes.