There were already cases where proofs were considered true and then later flaws where found that rendered them invalid. I think the answer is quite simple: if

There were already cases where proofs were considered true and then later flaws where found that rendered them invalid. I think the answer is quite simple: if something happens that contradicts the proof then a lot of resources will be used to doublecheck the proof and ensure its correctness and it will just be accepted that proofs are not always 100% valid.