Testing Base URI: better input checking

The test based uri in the asset hosting part of the extension manager page has instructions in small hard to read grey text, specifying the format for the uri. One of the pieces of text read “The URI must end with a forward slash.” However the input field does not require this or give you a warning if your uri does not end with a forward slash. This seems like a simple quality of life improvement that would have saved me the last 2 hours of debugging what I did wrong in trying to test my extension locally vs live.