Fixed crash when starting recording on map already visible

src/main/java/pl/llp/aircasting/screens/stream/map/AirCastingMapActivity.java

@@ -29,7 +29,6 @@
 import android.location.Location;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
-import android.os.AsyncTask;
 import android.os.Bundle;
 import android.support.v4.app.ActivityCompat;
 import android.view.MenuItem;
@@ -45,14 +44,12 @@
 import com.google.android.libraries.maps.SupportMapFragment;
 import com.google.android.libraries.maps.model.BitmapDescriptor;
 import com.google.android.libraries.maps.model.BitmapDescriptorFactory;
-import com.google.android.libraries.maps.model.JointType;
 import com.google.android.libraries.maps.model.LatLng;
 import com.google.android.libraries.maps.model.LatLngBounds;
 import com.google.android.libraries.maps.model.Marker;
 import com.google.android.libraries.maps.model.MarkerOptions;
 import com.google.android.libraries.maps.model.Polyline;
 import com.google.android.libraries.maps.model.PolylineOptions;
-import com.google.android.libraries.maps.model.RoundCap;
 import com.google.android.libraries.maps.model.SquareCap;
 import com.google.android.libraries.maps.model.StyleSpan;
 import com.google.common.eventbus.Subscribe;
@@ -168,6 +165,7 @@ private void drawSession() {
 
         options.addAll(measurementPoints).addAllSpans(measurementSpans);
         measurementsLine = map.addPolyline(options);
+
         drawLastMeasurementMarker(latestPoint, latestColor);
     }
 
@@ -371,6 +369,10 @@ public void run() {
                     measurementPoints.add(point);
                     measurementSpans.add(new StyleSpan(color));
 
+                    if (measurementsLine == null) {
+                        measurementsLine = map.addPolyline(options);
+                    }
+
                     measurementsLine.setPoints(measurementPoints);
                     measurementsLine.setSpans(measurementSpans);