Modify css support check to work better with SSR

[johnnyeric]

Hi @kazzkiq. Thanks for this project, it's great!

I've been experimenting the editor with Next.js and found an issue when using SSR on the CSS check.

It's a very simple fix but I took the liberty of creating this pull request.

Thank you

[kazzkiq]

Hello @johnnyeric, glad you liked CodeFlask!

Care to elaborate a little more about the issue with Next.js?

Shouldn't CSS be undefined both in client and SSR if it doesn't exists? In this case, the if(CSS) should handle both cases, why isn't it the case for Next.js?

[johnnyeric]

Sure, the problem is that when rendering on the server it seems the variable is not even declared so it throws when trying to access it in the if(CSS).

Then the typeof handles both cases, when it is not declared and when it is declared but is undefined.

The error message I get is CSS is not defined.

[kazzkiq]

Now it makes sense, merging it.

Thanks for the PR!