Error when not checking the count argument is an array

[nasri-lab]

PHP Fatal error: Uncaught TypeError: count(): Argument #1 ($value) must be of type Countable|array, null given in /Diff/SequenceMatcher.php:353

$aLength = count($this->a);
$bLength = count($this->b);

Please fix by replacing with this :

$aLength = is_array($this->a) ? count($this->a) : 0;
$bLength = is_array($this->b) ? count($this->b) : 0;