function set_required_validators_num(
        uint256 _required_validators
    ) external virtual onlyRole(MANAGER_ROLE) {
        uint256 old = required_validators;
        required_validators = _required_validators;
        emit RequiredValidatorsChanged(msg.sender, old, required_validators);
    }
function set_required_validators_num(
        uint256 _required_validators
    ) external virtual onlyRole(MANAGER_ROLE) {
+       require(_required_validators <= validator_count, "req exceeds current number of validators");
        uint256 old = required_validators;
        required_validators = _required_validators;
        emit RequiredValidatorsChanged(msg.sender, old, required_validators);
    }
