Interval.intersection() on abutting intervals returns a 0-length interval instead of null

[0x24a537r9]

Describe the bug
Interval.intersection() on abutting intervals returns a 0-length interval, in spite of https://moment.github.io/luxon/docs/class/src/interval.js~Interval.html#static-method-fromDateTimes saying that Interval is "Inclusive of the start but not the end". The docstring for intersection also says explicitly "Returns null if the intersection is empty, meaning, the intervals don't intersect."

To Reproduce

test('intersection of abutting intervals is null', () => {
  expect(
    Interval.fromISO('2021-01-01T09:00:00Z/2021-01-01T10:00:00Z').intersection(
      Interval.fromISO('2021-01-01T10:00:00Z/2021-01-01T11:00:00Z'),
    ),
  ).toBeNull();
});

Actual vs Expected behavior
If Interval is indeed meant to be inclusive of the start but not the end, then the overlap should be null. Instead I get for the test above:

    expect(received).toBeNull()

    Received: {"e": "2021-01-01T02:00:00.000-08:00", "invalid": null, "isLuxonInterval": true, "s": "2021-01-01T02:00:00.000-08:00"}

      1110 |         Interval.fromISO('2021-01-01T10:00:00Z/2021-01-01T11:00:00Z'),
      1111 |       ),
    > 1112 |     ).toBeNull();
           |       ^
      1113 |   });
      1114 |
      1115 |   // tech with null rules

It's worth noting that Interval.overlaps() works as expected, with the following test passing:

test('overlaps of abutting intervals is false', () => {
  expect(
    Interval.fromISO('2021-01-01T09:00:00Z/2021-01-01T10:00:00Z').overlaps(
      Interval.fromISO('2021-01-01T10:00:00Z/2021-01-01T11:00:00Z'),
    ),
  ).toBe(false);
});

Conceptually, I think that Interval.overlaps() should be perform identically to Interval.intersection() != null.

Desktop (please complete the following information):

• OS: Mac
• Browser: Node
• Luxon version: ^1.26.0