Are there any potential pitfalls in using strict comparison (===) with isset() in PHP code?

When using strict comparison (===) with isset() in PHP code, a potential pitfall is that isset() returns a boolean value (true or false), while strict comparison expects both the value and type to match. This can lead to unexpected results if not handled correctly. To solve this issue, you can use a combination of isset() and strict comparison to check if a variable is set and not null.

// Potential pitfall: using strict comparison with isset()
$var = null;

if ($var === isset($var)) {
    echo "Variable is set and not null";
} else {
    echo "Variable is not set or is null";
}

// Correct way: using isset() and strict comparison separately
if (isset($var) && $var !== null) {
    echo "Variable is set and not null";
} else {
    echo "Variable is not set or is null";
}