types/wlr_output: validate swapchain creation before destroying the current one

types/output/cursor.c

@@ -261,14 +261,15 @@ static struct wlr_buffer *render_cursor_buffer(struct wlr_output_cursor *cursor)
 			return NULL;
 		}
 
-		wlr_swapchain_destroy(output->cursor_swapchain);
-		output->cursor_swapchain = wlr_swapchain_create(allocator,
+		struct wlr_swapchain *swapchain = wlr_swapchain_create(allocator,
 			width, height, format);
 		free(format);
-		if (output->cursor_swapchain == NULL) {
+		if (swapchain == NULL) {
 			wlr_log(WLR_ERROR, "Failed to create cursor swapchain");
 			return NULL;
 		}
+		wlr_swapchain_destroy(output->cursor_swapchain);
+		output->cursor_swapchain = swapchain;
 	}
 
 	struct wlr_buffer *buffer =