Fixed issue win ResizableRaceCanvas

- Issue where the boat position may mess up if it is called before the server has sent us information about hte location.
#story[782]

visualiser/src/main/java/seng302/Model/ResizableRaceCanvas.java

@@ -84,17 +84,19 @@ public class ResizableRaceCanvas extends Canvas {
     }
 
     public void displayBoat(Boat boat, double angle, Color colour) {
-        GraphCoordinate pos = this.map.convertGPS(boat.getCurrentPosition());
-        Paint paint = colour;
-
-        double[] x = {pos.getX() - 6, pos.getX(), pos.getX() + 6};
-        double[] y = {pos.getY() + 12, pos.getY() - 12, pos.getY() + 12};
-        gc.setFill(paint);
-
-        gc.save();
-        rotate(angle, pos.getX(), pos.getY());
-        gc.fillPolygon(x, y, 3);
-        gc.restore();
+        if (boat.getCurrentPosition() != null) {
+            GraphCoordinate pos = this.map.convertGPS(boat.getCurrentPosition());
+            Paint paint = colour;
+
+            double[] x = {pos.getX() - 6, pos.getX(), pos.getX() + 6};
+            double[] y = {pos.getY() + 12, pos.getY() - 12, pos.getY() + 12};
+            gc.setFill(paint);
+
+            gc.save();
+            rotate(angle, pos.getX(), pos.getY());
+            gc.fillPolygon(x, y, 3);
+            gc.restore();
+        }
     }
 
     /**