Now catching error 500 in frontend.

Fixes #22

frontend/src/redux/api/SmartActions.js

@@ -130,11 +130,16 @@ export default class SmartActions {
           dispatch(isSavingSpecific(false));
         })
         .catch((e) => {
-          if (typeof e.json == "function") {
-            return e.json();
+          if (typeof e.json === "function") {
+            return e.json()
+              .catch((error) => {
+                // eslint-disable-next-line no-unused-vars
+                return new Promise((resolve, reject) => resolve(error));
+
+              });
           } else {
             // eslint-disable-next-line no-unused-vars
-            return new Promise(function (resolve, reject) { resolve(e); });
+            return new Promise((resolve, reject) => resolve(e));
           }
         })
         .then((errorContent) => {