Fix null ref

projects/common-map/src/fm-map/components/aol/gps-location/gps-location.component.ts

@@ -59,10 +59,12 @@ export class GpsLocation  implements OnInit,OnChanges{
   ngOnChanges(changes: SimpleChanges) {
     if (changes.position && this.instance) {
       var p = changes.position.currentValue as Position;
+      if(p) {
         this.instance.setPosition(fromLonLat([p.coords.longitude, p.coords.latitude]));
         this.locationTolerance = p.coords.accuracy;
         this.recalcLocationTolerance();  
       }
+    }
     if(changes.heading && this.instance) {
       this.rotate = "rotate(" +   Math.round(changes.heading.currentValue) + " 500 500)";
     }

projects/common-map/src/fm-map/services/geolocation.service.ts

@@ -1,5 +1,5 @@
 import { Injectable } from '@angular/core';
-import { Observer, Observable } from 'rxjs';
+import { Observer, Observable,BehaviorSubject } from 'rxjs';
 
 /**
  * GeolocationService class.
@@ -9,23 +9,15 @@ import { Observer, Observable } from 'rxjs';
 @Injectable()
 export class GeolocationService {
 
-  /**
+  private positionObserver$:BehaviorSubject<Position>  = new BehaviorSubject<Position>(null);
-   * Tries HTML5 geolocation.
+
-   *
+  constructor() {
-   * Wraps the Geolocation API into an observable.
-   *
-   * @return An observable of Position
-   */
-  getCurrentPosition(): Observable<Position> {
-    return Observable.create((observer: Observer<Position>) => {
-      // Invokes getCurrentPosition method of Geolocation API.
     navigator.geolocation.watchPosition(
       (position: Position) => {
-          observer.next(position);
+        this.positionObserver$.next(position);
       },
       (error: PositionError) => {
         console.debug('Geolocation service: ' + error.message);
-          //observer.error(error);
       },
       {
         enableHighAccuracy: true,
@@ -33,7 +25,10 @@ export class GeolocationService {
         maximumAge: 0
       }
     );
-    });
   }
 
+
+  getCurrentPosition(): Observable<Position> {
+    return this.positionObserver$;
+  }
 }