Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xls/Parser.php
private function convertError($errorCode)
    {
        switch ($errorCode) {
            case '#NULL!':
                return pack('C', 0x00);
            case '#DIV/0!':
                return pack('C', 0x07);
            case '#VALUE!':
                return pack('C', 0x0F);
            case '#REF!':
                return pack('C', 0x17);
            case '#NAME?':
                return pack('C', 0x1D);
            case '#NUM!':
                return pack('C', 0x24);
            case '#N/A':
                return pack('C', 0x2A);
        }

        return pack('C', 0xFF);
    }
private function convertError($errorCode)
    {
        switch ($errorCode) {
            case '#NULL!':
                return pack('C', 0x00);
            case '#DIV/0!':
                return pack('C', 0x07);
            case '#VALUE!':
                return pack('C', 0x0F);
            case '#REF!':
                return pack('C', 0x17);
            case '#NAME?':
                return pack('C', 0x1D);
            case '#NUM!':
                return pack('C', 0x24);
            case '#N/A':
                return pack('C', 0x2A);
        }

        return pack('C', 0xFF);
    }
Convert an error code to a ptgErr.

@param string $errorCode The error code for conversion to its ptg value

@return string The error code ptgErr