hex to address function is wrong

[dshiell]

Should verify hex characters and implement proper error checking. Should look like:

* Converts a hexadecimal string to an address.
 * Assumes the hexadecimal string is prefixed with "0x".
 * @param _hexStr The hexadecimal string to convert.
 * @return addr The address converted from the hexadecimal string.
 */
function hexStrToAddress(string memory _hexStr) public pure returns (address addr) {
    bytes memory hexBytes = bytes(_hexStr);

    // Check if the string has an appropriate length: 2 characters for "0x" and 40 characters for the address
    require(hexBytes.length == 42, "Invalid length of the hexadecimal string.");

    uint160 total = 0;
    uint160 base = 1;
    for (uint256 i = hexBytes.length - 1; i >= 2; i--) {
        uint160 digit;
        // Convert ASCII to integer value
        if (uint8(hexBytes[i]) >= 48 && uint8(hexBytes[i]) <= 57) {
            // '0' to '9'
            digit = uint160(uint8(hexBytes[i]) - 48);
        } else if (uint8(hexBytes[i]) >= 65 && uint8(hexBytes[i]) <= 70) {
            // 'A' to 'F'
            digit = uint160(uint8(hexBytes[i]) - 55);
        } else if (uint8(hexBytes[i]) >= 97 && uint8(hexBytes[i]) <= 102) {
            // 'a' to 'f'
            digit = uint160(uint8(hexBytes[i]) - 87);
        } else {
            revert("Invalid character in the hexadecimal string.");
        }
        total += digit * base;
        base *= 16;
    }

    return address(total);
}

}