Remove whitespaces from vocabulary links, add dedicated exception for

lcsh links that are actually loc links

exceptions/MDInvalidNodaLinkLcshIdIsGeneralLoc.php

@@ -0,0 +1,20 @@
+<?PHP
+declare(strict_types = 1);
+
+/**
+ * Exception thrown in case a library of congress subject headings link refers
+ * to the other authority files of the Library of Congress.
+ */
+final class MDInvalidNodaLinkLcshIdIsGeneralLoc extends MDInvalidNodaLinkException {
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        return 'Inputs are not valid.';
+
+    }
+}
+