fix: A task may only be disposed if it is in a completion state (RanToCompletion, Faulted or Canceled). (#318)

Author: jetelain

GameRealisticMap/Satellite/SatelliteImageProvider.cs

@@ -135,11 +135,10 @@ public async Task<Rgba32> GetPixel(GeoAPI.Geometries.Coordinate coordinate)
 
         private void ClearCache()
         {
-            foreach (var img in cache.Values)
-            {
-                img.Dispose();
-            }
-            cache.Clear();
+            // Just clear the reference to the images, and let the GC do the work to release memory,
+            // as we don't know if a thread has still a reference to one of the images
+            // The synchronization overhead is not worth it.
+            cache.Clear(); 
             estimatedCachePressure = 0;
         }