Fix lint.

Fix lint.

diff --git a/assets/javascripts/initializers/discourse-graphviz.js.es6 b/assets/javascripts/initializers/discourse-graphviz.js.es6
index c3360e1..4718d30 100644
--- a/assets/javascripts/initializers/discourse-graphviz.js.es6
+++ b/assets/javascripts/initializers/discourse-graphviz.js.es6
@@ -49,7 +49,7 @@ export default {
   initialize() {
     withPluginApi("0.8.22", api => {
       api.decorateCooked(
-        ($elem, helper) => {
+        ($elem, _helper) => {
           if (!Discourse.SiteSettings.discourse_graphviz_enabled) {
             return;
           }

GitHub sha: a3ad0edc