Placing a 4th item on a champion destroys said item. Intended?

I, in a misclick error, tried placing a 4th basic item onto a champion which was already completely full on completed items. I was NOT given the item in question back to place on an eligible champion. It simply disappeared altogether. Is this a bug or is this a gameplay mechanic designed to punish those who simply make simple errors?

I feel completely robbed as I could very well have finished 2nd or even 1st instead of 3rd because the matches were JUST. THAT. CLOSE.