formState example is broken

[kristian240]

Describe the bug
Codepen example for formState object breaks when there are errors. JSON.stringify can't convert circular reference

To Reproduce
Steps to reproduce the behavior:

1. Open formStateexample link
2. Set Number of Corndogs number input to negative number or positive number greater than 99
3. Press submit

Codesandbox link (Required)
Include a codesandbox will help us to investigate the issue quicker.

https://codesandbox.io/s/react-hook-form-v6-formstate-ht098

Expected behavior
A clear and concise description of what you expected to happen.

formState should be printed beneath the form.

Screenshots

Desktop (please complete the following information):

• OS: MacOS - Big Sur
• Browser - latest Chrome (v87.0.4280.88)

Additional context

I would like to work on this if possible 😄

[bluebill1049]

thanks @kristian240 fixed 👍