Stringify can return undefined

Author: zalmoxisus

src/app/api/index.js

@@ -32,7 +32,7 @@ function stringify(obj, serialize) {
   const str = typeof serialize === 'undefined' ? tryCatchStringify(obj) :
     jsan.stringify(obj, serialize.replacer, null, serialize.options);
 
-  if (!stringifyWarned && str.length > 16 * 1024 * 1024) { // 16 MB
+  if (!stringifyWarned && str && str.length > 16 * 1024 * 1024) { // 16 MB
     /* eslint-disable no-console */
     console.warn('Application state or actions payloads are too large making Redux DevTools serialization slow and consuming a lot of memory. See https://git.io/fpcP5 on how to configure it.');
     /* eslint-enable no-console */