Fix possible double release

Author: Jack251970

Flow.Launcher.Infrastructure/Image/ThumbnailReader.cs

@@ -62,6 +62,7 @@ private static unsafe HBITMAP GetHBitmap(string fileName, int width, int height,
             if (nativeShellItem is not IShellItemImageFactory imageFactory)
             {
                 Marshal.ReleaseComObject(nativeShellItem);
+                nativeShellItem = null;
                 throw new InvalidOperationException("Failed to get IShellItemImageFactory");
             }
 
@@ -86,7 +87,10 @@ private static unsafe HBITMAP GetHBitmap(string fileName, int width, int height,
             }
             finally
             {
-                Marshal.ReleaseComObject(nativeShellItem);
+                if (nativeShellItem != null)
+                {
+                    Marshal.ReleaseComObject(nativeShellItem);
+                }
             }
 
             return hBitmap;