templates: make sure we don't call register routes if this function is not defined.

- prevents simple JS errors on 4XX and 5XX pages.

rhodecode/public/js/src/rhodecode/init.js

@@ -21,6 +21,9 b''
  * Deferred functions that must run before any rhodecode javascript go here
  */
 
+
+if (typeof window['registerRCRoutes'] != 'undefined') {
 registerRCRoutes();
+}
 
 // TODO: move i18n here