'vigo-b'如何是提交表格中的不允许的关键字符

Question

Please see 2 pictures.

enter image description here

First one is a table with multi form fields. When I press submit.

enter image description here

Coidegniter show error like second picture.

What is the problem with vigo-b? hyphen? I think hyphen is an allowed key character here.

here is the input function in system/core folder

function _clean_input_keys($str)
{

// UPDATE: Now includes comprehensive Regex that can process escaped JSON

if (!preg_match("/^[a-z0-9\:\;\.\,\?\!\@\#\$%\^\*\"\~\'+=\\\ &_\/\.\[\]-\}\{]+$/iu ", $str))
    {
    /**
     * Check for Development enviroment - Non-descriptive
     * error so show me the string that caused the problem
     */
    if (getenv('ENVIRONMENT') && getenv('ENVIRONMENT') == 'DEVELOPMENT')
        {
        var_dump($str);
        }

    exit('Disallowed Key Characters.' . $str);
    }

// Clean UTF-8 if supported

if (UTF8_ENABLED === TRUE)
    {
    $str = $this->uni->clean_string($str);
    }

return $str;
}