Saw NZ90 on approach when I heard ATC mention a Dash8 reported a broken landing light and were unsure if it happend on landing on enroute. Pilots on NZ90 decided to take go around option whilst the runway was checked. Great view of the belly of NZ90 as she fly overhead following the runway. No glass found. NZ90 landed fine. The flight was direct from Tokyo as Chch is not accepting International flights at this time.