Error with Geocode API in Ionic 2

Question

I’m using the Google Maps Geocode API to read an address and place a marker on the map. This is how I’m using it :

for(let marker of markers){
this.geocoder = new google.maps.Geocoder();
this.geocoder.geocode({
 'address': marker["address"]
}, (results,status) => {  
          var position = new google.maps.LatLng(results[0].geometry.location.lat(),results[0].geometry.location.lng()); // error pointing to this line
          this.personMarker = new google.maps.Marker({position: position, title: marker.name, markerInfo: marker, map : this.map , icon : marker.imageurl});
          google.maps.event.addListener(this.personMarker, 'click',  () => {
          this.showCard = true;
          this.org = marker.organization;
          this.gig = marker.gig;
          this.location = marker["address"];
          this.image = marker.imageurl;
          this.ngoData = marker;
          this.ownerusername = marker.ownerusername;
            });
     });
 }

I get this error: ‘Cannot read property ‘0’ of null’ pointing to the line I’ve shown with a comment in the code snippet.Just don’t know what’s causing that error because I’m accessing the ‘results’ parameter only inside the callback. console.log(results) sometimes returns 'null' for the first iteration of the loop, followed by proper results for the rest of the iterations, or proper results for all iterations. I don't understand this inconsistent behavior, but I do know that I get this error usually when the intervals between me clicking and loading the map again is short.

I know that all the addresses are valid because sometimes all my markers appear on the map and the error doesn't turn up