Not panic when we ADD more signatures than required.

[Ethnical]

During an execution if one of the signer was a nested safe this and we add more signature this will cause a panic because the array is too big..

This is because the code here append the signature with the address making the array to big and will iterate on an incorrect count instead of counting the exact number of sig this will count the exact number of sig + 1.
Like this:

    function prepareSignatures(
        address _safe,
        bytes32 hash,
        bytes memory _signatures
    ) internal view returns (bytes memory) {
        // prepend the prevalidated signatures to the signatures
        address[] memory approvers = getApprovers(_safe, hash);
        bytes memory prevalidatedSignatures = genPrevalidatedSignatures(
            approvers
        );
        _signatures = bytes.concat(prevalidatedSignatures, _signatures); //Not sure why this also append the nested approver (signer that used the ApprovalHash method). 

https://github.com/base-org/contracts/blob/494586571e1a4d845ee6f381b65229d63c630986/script/universal/Signatures.sol#L18