error handling + cleanup

- handle case where localstorage does not contain item
- eventhandler updates when data changes

client/src/App.css

@@ -3,8 +3,10 @@
   -moz-osx-font-smoothing: grayscale;
 }
 
+body,
+html,
 .App {
   margin: 0px auto;
   overflow: hidden;
   height: 100vh;
-}
+}