Check if there is a current route defined before getting the action

This fixes an issue I discovered when a Laravel before filter returns a response.

Author: weotch

src/Intouch/LaravelNewrelic/LaravelNewrelicServiceProvider.php

@@ -107,7 +107,7 @@ public function getTransactionName( $request, $response, $app )
             $router = $app['router'];
 
             $name = $router->currentRouteName()
-                ?: $router->currentRouteAction()
+                ?: $router->current() && $router->currentRouteAction()
                 ?: $request->getMethod() . ' ' . $request->getPathInfo();
         }