rxJs scan - doesn't emit if observable is empty - rxjs

Question

I have a bit of code that looks like this:
function getEvensSquared(array) {
return rxjs.of(array).pipe(
rxjs.operators.flatMap(array => {
return rxjs.from(
array.filter(n => n % 2 === 0)
);
}),
rxjs.operators.switchMap(n => {
return rxjs.of(n * n);
}),
rxjs.operators.scan((acc, cur) => {
acc.push(cur);
return acc;
}, [])
);
}
getEvensSquared([1, 2, 3, 4]).subscribe(v => {
console.log("1,2,3,4");
console.log(v)
});
getEvensSquared([1, 3, 5]).subscribe(v => {
console.log("1,3,5"); //never prints
console.log(v)
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.2.2/rxjs.umd.min.js"></script>
Essentially it is:
Get a stream of arrays of ObjectA.
Convert the array in to a stream of filtered ObjectA.
Convert the stream of ObjectA into a stream of ObjectB.
Accumulate the stream of ObjectB into a stream of arrays of ObjectB.
The problem is - if there are no approved bookings, the flatMap operator never emits. Is there a way to default in this case?
I tried putting defaultIfEmpty([]) after the scan - but that didn't work.

Answer 1

Positing this as an answer - because it works for the example I've given - defaultIfEmpty does work in this scenario.
function getEvensSquared(array) {
return rxjs.of(array).pipe(
rxjs.operators.flatMap(array => {
return rxjs.from(
array.filter(n => n % 2 === 0)
);
}),
rxjs.operators.switchMap(n => {
return rxjs.of(n * n);
}),
rxjs.operators.scan((acc, cur) => {
acc.push(cur);
return acc;
}, []),
rxjs.operators.defaultIfEmpty([])
);
}
getEvensSquared([1, 2, 3, 4]).subscribe(v => {
console.log("1,2,3,4");
console.log(v)
});
getEvensSquared([1, 3, 5]).subscribe(v => {
console.log("1,3,5"); //works
console.log(v)
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/6.2.2/rxjs.umd.min.js"></script>