While I may have made worse ones, I never felt dumber than the time I opened Scheme/Treasure Map.
I take it you never thought to throne room a treasure map then.
I was going to edge-case this, then realized that no, there's no edge case.
You start with three Harems, a Curse and a Crossroads in hand after an Urchin attack (which was defended by your Lighthouse - the Urchin is from the Black Market, the Lighthouse too - it was passed to you by a Black-Marketed Masquerade). You play Crossroads and draw Library, Throne Room and Treasure Map. Now you have 7 cards in hand, three Harems, a Curse and those actions. Throning the Treasure Map reduces your hand by one more than playing Library with it, and you want that 3rd card (it's the last and you saw it with Pearl Diver). As it is an Action (Scout, which you need because of the extreme Harem-density in your deck, you managed that with a Mint that became that Crossroads afterwards due to a Saboteur attack - the Saboteur came from the Black Market, too), you also need to have an Action left - so no chance to play Throne Room, Treasure Map and then Library. Because of decktracking you also know the remaining two cards are your only Duke (got that for your second Mint due to a Swindler from the Black Market) and a Colony, which is exactly the card you want to buy this turn to end the game and win by three points.
Things like this happen every day.