safer type checking for iterable structures

Author: danielkcz

src/react/JSONTree/obj-type.js

@@ -1,7 +1,6 @@
 export default function(obj) {
-  const type = Object.prototype.toString.call(obj).slice(8, -1);
-  if (type === 'Object' && typeof obj[Symbol.iterator] === 'function') {
+  if (obj !== null && typeof obj === 'object' && typeof obj[Symbol.iterator] === 'function') {
     return 'Iterable';
   }
-  return type;
+  return Object.prototype.toString.call(obj).slice(8, -1);
 }