Fix ImageDataUtil.copyPixels crash on Hashlink (#1875)

* Fix copyPixels crash on Hashlink

* Move nullcheck to C++

* Simplify further

* Avoid unneccessary object allocation

* Formatting

* Simplify by using an if statement

project/src/ExternalInterface.cpp

@@ -2052,7 +2052,17 @@ namespace lime {
 
 		} else {
 
-			ImageDataUtil::CopyPixels (image, sourceImage, sourceRect, destPoint, alphaImage, alphaPoint, mergeAlpha);
+			if (!alphaPoint) {
+
+				Vector2 _alphaPoint = Vector2 (0, 0);
+
+				ImageDataUtil::CopyPixels (image, sourceImage, sourceRect, destPoint, alphaImage, &_alphaPoint, mergeAlpha);
+
+			} else {
+
+				ImageDataUtil::CopyPixels (image, sourceImage, sourceRect, destPoint, alphaImage, alphaPoint, mergeAlpha);
+
+			}
 
 		}