Define theft.
If you write a contract and give it to a lawyer with the instruction, "Anyone who satisfies this contract gets this money." And someone satisfies the contract to the lawyer's -but not your- satisfaction, and the lawyer sends the money, did the third party steal from you?
There's a very relevant XKCD on this, where someone discovers a clever "bug" in an insurance contract, and is then disappointed.
https://xkcd.com/1494/