Rated 4 out of 5 stars

Excellent app, very useful and perfectly working. However I had to fiddle with it for half an hour before getting it to work. I was trying to remove a part of an URL and I did not know that empty replace field was not allowed. The extension does not report the fact and simply does not execute the rule. Could you please allow for blank replace field or at least print some error message so that users don't have to figure out by useless attempts what is the issue?