Fix invalid default sender address for email reports

MDErrorReporter.php

@@ -233,7 +233,7 @@ final public function sendErrorReport(Throwable $exception, string $recipient, s
      *
      * @return void
      */
-    public function __construct(string $toolName = "museum-digital (unspecified)", string $contact_mail_addr = "bugs-md") {
+    public function __construct(string $toolName = "museum-digital (unspecified)", string $contact_mail_addr = "bugs-md@museum-digital.de") {
 
         $this->_context = $toolName;
         $this->_contact_mail_addr = $contact_mail_addr;