Cleanup isEmpty function (#1621)
Cleanup isEmpty function (#1621)

`null` values were going down the isEmptyObject code path. There was a check that type !== null (but it never will be, I think the intent was to check the value not the type).
Just exit early for null cases and stop worrying about them later on in the function.

isEmptyArray was checking if the value was undefined, which we already know its not.

Same with isEmptyPrimative; we already know its not undefined, why check again.
sanity-io/sanity,sanity-io/sanity,sanity-io/sanity,sanity-io/sanity