Hi mate, I had/have the exact same issue. Put in LED bulbs and all was fine for about a week. Then the passenger bulb wasn't working and I was getting a warning light on the dash. Tried a regular 50p sidelight bulb in it and it wouldn't work either???
Someone on here recommended fuses, sidelights are f25 and f26 in fusebox under the bonnet (your user manual will help you locate these). I took these out and put them back in again to see if the fault cleared and as if by magic both lights were now working and no more dash warning.
All I will say is every now and again I will get the same warning on the dash but it seems to keep clearing itself. Think LED sidelights are a bit of a hit or a miss to be honest.
Hope this helps you out.