Improve determinism

phpcs-errors:226 phpunit-status:successful phpstan-errors:199

index6.php

@@ -33,7 +33,9 @@
 if (is_dir(__DIR__ . "/xml")) rrmdir(__DIR__ . '/xml');
 mkdir(__DIR__ . "/xml", 0755);
 
-$fp = fopen ($csv_datei, 'r');
+if (!($fp = fopen($csv_datei, 'r'))) {
+    throw new MDmainEntityNotExistentException("Failed opening file");
+}
 $y = 0;
 while ($zeile = fgetcsv($fp, 100000, ';')) {