PHP注意：第10行的数组到字符串转换

I am a newbie and have written some code in PHP which gives me above mentioned notice. My program works perfectly but i want to resolve the notice. I know i can turn off the notice, but i dont want to do that. Please let me know how can i fix it.

My code -

$GLOBALS['config'] = array(
    'mysql' =>  array(
        'host'  =>  '127.0.0.1',
        'username'  =>  'root',
        'password'  =>  '',
        'database'  =>  'app'
    )
);


            $config = $GLOBALS['config'];
            $path = explode('/', 'mysql/host');

            foreach($path as $bit){                
                if(isset($config[$bit])){
                    $config = $config[$bit];
                }
            }

            echo $config;

My output from

echo $config;

is 127.0.0.1 and it is as expected.

But i am getting the notice on line -

$config = $GLOBALS['config'];

Please help.

Try adding this line right before the $config = $GLOBALS['config']

$config = array();