What are some best practices for debugging PHP scripts that involve XPath queries?

When debugging PHP scripts that involve XPath queries, it is important to check the XPath expression being used and ensure it is correctly targeting the desired elements in the XML document. Additionally, it can be helpful to use tools like XPath online testers to validate the XPath expression. Finally, consider using functions like `xpath()` in PHP to retrieve and display the results of the XPath query for easier debugging.

// Example PHP code snippet for debugging XPath queries
$xml = '<root><element1>Value 1</element1><element2>Value 2</element2></root>';
$doc = new DOMDocument();
$doc->loadXML($xml);

$xpath = new DOMXpath($doc);
$query = '/root/element1';

$results = $xpath->query($query);

if ($results->length > 0) {
    foreach ($results as $result) {
        echo $result->nodeValue;
    }
} else {
    echo 'No results found for XPath query: ' . $query;
}