Does it make sense to throw a type error if the value cannot be null for the `.toBeNull` helper?

Does it make sense to throw a type error if a value cannot be null for the .toBeNull helper? For example, in the following test I WOULD expect a type error if the type cannot be null:

  it("cannot be null", () => {
    const x: number = 1;
    expect(x).toBeNull(); # Throw a type error here since `x` can only be a number?
  });

I WOULD NOT expect a type error if the value can be null. For example, in this test:

  it("cannot be null", () => {
    const x: number | null = 1;
    expect(x).toBeNull();
  });

Let me know if that makes sense.

Start by reviewing the .toBeNull helper and the TypeScript examples in the issue. The work first needs a decision on whether non-nullable values should produce a type error, followed by defining and verifying the expected behavior for nullable and non-nullable values.