feat: harden xml parsing to avoid uncaught errors

src/BusProNet/XmlParser/ContactFormResponseParser.php

@@ -11,8 +11,12 @@ class ContactFormResponseParser extends AbstractParser
 {
     public function parse(Crawler $node): RegistrationResponse
     {
-        $addressId = (int) $node->filterXPath('//idadresse')->text();
-        $personId = (int) $node->filterXPath('//idperson')->text();
+        $addressId = $this->getIntOrNullValue($node->filterXPath('//idadresse'));
+        $personId = $this->getIntOrNullValue($node->filterXPath('//idperson'));
+        if (null === $addressId || null === $personId) {
+            throw new \InvalidArgumentException('Missing required idadresse or idperson in contact form response.');
+        }
+
         $isNewRecord = $this->getBoolValue($node->filterXPath('//neuanlage'));
 
         return new RegistrationResponse(