Error logging added

src/engine/InterestManagement/Terrain.java

@@ -12,6 +12,7 @@ import engine.gameManager.ZoneManager;
 import engine.math.Vector2f;
 import engine.math.Vector3fImmutable;
 import engine.objects.Zone;
+import org.pmw.tinylog.Logger;
 
 import java.util.HashMap;
 
@@ -42,6 +43,9 @@ public class Terrain {
 
         this.terrain_pixel_data = Terrain._heightmap_pixel_cache.get(heightmap);
 
+        if (terrain_pixel_data == null)
+            Logger.error("Pixel map empty");
+
         this.cell_count.x = this.terrain_pixel_data.length - 1;
         this.cell_count.y = this.terrain_pixel_data[0].length - 1;