关于COUNT（''）的事情

I found a question in php7.3.4.

if ( count( '' ) == 1 )
{
    echo 1;
}  else {
    echo 2;
}

This program output 1.Then I checked the source for the function 'count'.

PHP_FUNCTION(count)
{
    ....
    switch (Z_TYPE_P(array)) {
        case IS_NULL:
            php_error_docref(NULL, E_WARNING, "Parameter must be an array or an object that implements Countable");
            RETURN_LONG(0);
        break;
        case IS_ARRAY:
            ...
        break;
        case IS_OBJECT:
            ....
        break;
        default:
            php_error_docref(NULL, E_WARNING, "Parameter must be an array or an object 
            that implements Countable");
            RETURN_LONG(1);
        break;
}

This is easy to producing BUG. I think it count('') maybe output error or 0 is better than 1 and a Warning. What do you think about? And count(NULL) is not equal to count(''),It feels strange.

From count() docs:

Returns the number of elements in array_or_countable. When the parameter is neither an array nor an object with implemented Countable interface, 1 will be returned.

count('') thus returns 1, just like count('seventeen') returns 1. Working as intended.