fix: make bpn response failures diagnosable

src/BusProNet/XmlParser/ApiResponseParser.php

@@ -17,7 +17,7 @@ class ApiResponseParser extends AbstractParser
         $crawler = XmlCrawlerFactory::create($xml);
 
         if (0 === $crawler->count()) {
-            throw new ResponseParserException('Empty response received from server');
+            throw new ResponseParserException('Unable to parse XML response: '.XmlCrawlerFactory::diagnose($xml));
         }
 
         // Override type unless present in XML to catch error responses
@@ -56,7 +56,8 @@ class ApiResponseParser extends AbstractParser
                         case 'Vorgangdruck':
                             return (new DocumentsParser())->parseConfirmation($resultNode);
                     }
-                    break;
+
+                    throw new ResponseParserException(sprintf('Unrecognised customer data subtype "%s"', $subType));
                 case ApiClient::TYPE_BASE_DATA_COUNTRIES:
                     return (new CountriesParser())->parse($resultNode);
                 case ApiClient::TYPE_MUTABLE_DATA:
@@ -92,6 +93,6 @@ class ApiResponseParser extends AbstractParser
             throw new ResponseParserException('Invalid XML response structure: '.$e->getMessage(), 0, $e);
         }
 
-        throw new ResponseParserException('Unable to parse XML response');
+        throw new ResponseParserException(sprintf('Unrecognised BusProNet response type "%s"', $responseType));
     }
 }