Contractual mistake
An area of contract law beloved of university professors and their students.
One thing to be clear: if you make an error what you agree with your counterparty, but your counterparty understands it and agrees it — that’s not a contractual mistake in a legal sense. It's just your screw up, and you’re stuck with it, barring the good graces of a beneign counterparty who might deign to let you out. You did a bad trade, hotshot.