Add exception class MDInvalidNodaLink

exceptions/updates/MDInvalidNodaLink.php

@@ -0,0 +1,24 @@
+<?PHP
+/**
+ * This file contains an exception class for usage of invalid noda links.
+ *
+ * @author Joshua Ramon Enslin <joshua@museum-digital.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Custom exception class to be raised when trying to use a language that is not
+ * accepted by museum-digital.
+ */
+final class MDInvalidNodaLink extends Exception {
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        return 'The noda link is not valid: ' . $this->getMessage();
+
+    }
+}