When setting a prop to null a warning is firing: Cannot read property 'type' of null

[Tzelon]

Describe the bug
When setting a prop to null a warning is firing:
Cannot read property 'type' of null

To Reproduce

1. Click the yellow box and watch the console.
2. Drag the yellow box and you will see this warning fires multiple times.
   https://codesandbox.io/s/craftjs-cannot-read-property-type-of-null-czjmm?file=/src/App.tsx

Expected behavior
No warning. props can be null.

Your environment

Software	Version(s)
craft.js	0.1.0-beta.8
React	16.12.0

[prevwong]

Hey @Tzelon 👋 Thanks for the sandbox demo, it was really helpful! The issue seems to have been the serialising function, the fix is now in 0.1.0-beta.9!