What are the potential pitfalls of using the Null Coalescing Operator in PHP functions?

When using the Null Coalescing Operator in PHP functions, one potential pitfall is that it may not work as expected if the variable being checked is an empty string or a numeric 0. To solve this issue, you can use the `isset()` function to check if the variable is set and not null before using the Null Coalescing Operator.

// Potential pitfall with Null Coalescing Operator
$var = "";
$result = $var ?? "default"; // $result will be set to "default" instead of an empty string

// Fix using isset() function
$result = isset($var) ? $var : "default"; // $result will be set to an empty string as expected