Given a search string, fetch all movies results from the api
I think it's cool that you fetch the pages in parallel.

A minor miss of the spec

The description says to not return from getMovieTitles,
but the implementation does that.

I agree the early return makes sense when there is a single page of results.
I would have extracted to a function the code that fetches results.
Then the caller could simply call sortAndPrintResults on the returned array.

Things I find weird

return sortAndPrintResults(matches) is weird because sortAndPrintResults is void.

sortAndPrintResults joins the results before printing to console,
which doubles the memory used by the results.
It would have been better to call console.log in a loop.

I find the name fillRange misleading.
Basically it creates a sequence of numbers.
That's not what I would guess from the name.

It's a pity to construct an array of numbers just to loop over them.

These two issues could be fixed by implementing a range function as an async generator.

It's not 100% clear if the functions were given or only the first one.
Many of them would be better inlined.