feat: harden xml parsing to avoid uncaught errors

src/BusProNet/XmlParser/PersonalDataParser.php

@@ -57,7 +57,7 @@ class PersonalDataParser extends AbstractParser
         $remarksNode = $addressDataNode->filterXPath('//bemerkung');
 
         if (0 < $remarksNode->count()) {
-            $personalData->remarks = $remarksNode->text();
+            $personalData->remarks = $this->getStringOrNullValue($remarksNode);
         }
 
         return $personalData;