Apply suggestions from code review

Co-Authored-By: Neale Pickett <neale@woozle.org>

theme/moth-pwa.js

@@ -1,7 +1,8 @@
 function pwa_init() {
   if ('serviceWorker' in navigator) {
     navigator.serviceWorker.register("./sw.js").then(function(reg) {
-    }).catch(function(err) {
+    })
+    .catch(err => {
       console.warn("Error while registering service worker", err)
     })
   } else {

theme/moth.js

@@ -133,7 +133,8 @@ function drawCacheButton(teamId) {
         } else {
           cacher.style.display = "none"
         }
-      }).catch( ex => {
+      })
+      .catch(ex => {
           cacher.style.display = "none"
       })
   }