Can Hard Bargain be played without a spell on the chain? Just to fizzle?

No, Hard Bargain cannot be played if there is no spell on the chain.

According to RiftJudge FAQ #9898, Hard Bargain requires a target ("Counter a spell..."). To play a card, you must be able to choose a legal target at the time you place the spell on the chain. If there are no spells on the chain, there are no valid targets, and therefore it is an illegal move to attempt to play Hard Bargain.

Furthermore, per Rule 358.1, you must check that all chosen targets are legal when you play a card. If you cannot choose a legal target, the action of playing that card is illegal and will be cancelled.