fix: fixed crashing on circular React elements (#619)

* fix: fixed crashing on circular React elements

* chore: adjust a test implementation to be more meaningful

src/formatter/sortObject.js

@@ -1,13 +1,18 @@
 /* @flow */
+import * as React from 'react';
 
 export default function sortObject(value: any): any {
   // return non-object value as is
   if (value === null || typeof value !== 'object') {
     return value;
   }
 
-  // return date and regexp values as is
-  if (value instanceof Date || value instanceof RegExp) {
+  // return date, regexp and react element values as is
+  if (
+    value instanceof Date ||
+    value instanceof RegExp ||
+    React.isValidElement(value)
+  ) {
     return value;
   }
 

src/index.spec.js

@@ -1334,4 +1334,25 @@ describe('reactElementToJSXString(ReactElement)', () => {
 
     expect(reactElementToJSXString(<Lazy />)).toEqual(`<Lazy />`);
   });
+
+  it('should stringify `forwardRef` element with a circular property', () => {
+    function TagList({ tags }) {
+      return tags;
+    }
+
+    const Tag = React.forwardRef(function Tag({ text }, ref) {
+      return <span ref={ref}>{text}</span>;
+    });
+    Tag.emotionReal = Tag;
+
+    expect(
+      reactElementToJSXString(
+        <TagList tags={[<Tag key="oops" text="oops, circular" />]} />
+      )
+    ).toEqual(`<TagList
+  tags={[
+    <Tag key="oops" text="oops, circular"/>
+  ]}
+ />`);
+  });
 });