explorer: better root dnd

fixes #35032

src/vs/workbench/parts/files/electron-browser/views/explorerViewer.ts

@@ -661,10 +661,6 @@ export class FileDragAndDrop extends SimpleFileResourceDragAndDrop {
 	}
 
 	private statToResource(stat: FileStat): URI {
-		if (stat.isRoot) {
-			return null; // Can not move root folder
-		}
-
 		if (stat.isDirectory) {
 			return URI.from({ scheme: 'folder', path: stat.resource.path }); // indicates that we are dragging a folder
 		}
@@ -746,6 +742,10 @@ export class FileDragAndDrop extends SimpleFileResourceDragAndDrop {
 					return true; // NewStatPlaceholders can not be moved
 				}
 
+				if (source.isRoot) {
+					return true; // Root folder can not be moved
+				}
+
 				if (source.resource.toString() === target.resource.toString()) {
 					return true; // Can not move anything onto itself
 				}