The DragEvent should inherit from MouseEvent.

Reference: https://developer.mozilla.org/en-US/docs/Web/API/DragEvent

react/react.d.ts

@@ -287,7 +287,7 @@ declare namespace __React {
         data: string;
     }
 
-    interface DragEvent extends SyntheticEvent {
+    interface DragEvent extends MouseEvent {
         dataTransfer: DataTransfer;
     }