JS Spread syntax for arrays vs objects

Noticed a small quirk today in the JavaScript spread syntax: If you have three values:

const a = null;
const b = { x: 1 };
const c = [2];

Then the spread syntax for objects will work just fine

expect({ ...a, ...b }).toStrictEqual({ x: 1 });

While the spread syntax for arrays will throw a TypeError: a is not iterable:

expect([...a, ...c]).toThrow();

So the handling of null is different for these two cases. Interestingly typeof null seems to return object, while Object.keys(null) throws TypeError: Cannot convert undefined or null to object.

At the same time, typeof undefined === 'undefined' but the same seems to happen for a = undefined for the spread syntax (error for arrays, fine for objects).