What are the potential issues when upgrading PHP versions, specifically from 7.1 to 7.2, in relation to the count() function?

When upgrading PHP versions from 7.1 to 7.2, the count() function's behavior changed slightly. In PHP 7.1, count() would return 0 for null values, while in PHP 7.2, it throws a warning and returns 1. To fix this issue, you should check if the variable is null before calling count().

// Check if the variable is null before using count()
if ($variable !== null) {
    $count = count($variable);
} else {
    $count = 0;
}