only add first backend to multi autocreate

backend/backend.c

@@ -33,6 +33,10 @@ bool wlr_backend_start(struct wlr_backend *backend) {
 }
 
 void wlr_backend_destroy(struct wlr_backend *backend) {
+	if (!backend) {
+		return;
+	}
+
 	wl_signal_emit(&backend->events.destroy, backend);
 	if (backend->impl && backend->impl->destroy) {
 		backend->impl->destroy(backend);
@@ -82,6 +86,7 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		struct wlr_backend *wl_backend = attempt_wl_backend(display);
 		if (wl_backend) {
 			wlr_multi_backend_add(backend, wl_backend);
+			return backend;
 		}
 	}
 
@@ -90,18 +95,25 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 		struct wlr_backend *x11_backend =
 			wlr_x11_backend_create(display, x11_display);
 		wlr_multi_backend_add(backend, x11_backend);
+		return backend;
 	}
 
 	// Attempt DRM+libinput
 	struct wlr_session *session = wlr_session_create(display);
 	if (!session) {
 		wlr_log(L_ERROR, "Failed to start a DRM session");
-		goto out;
+		wlr_backend_destroy(backend);
+		return NULL;
 	}
 
 	struct wlr_backend *libinput = wlr_libinput_backend_create(display, session);
 	if (libinput) {
 		wlr_multi_backend_add(backend, libinput);
+	} else {
+		wlr_log(L_ERROR, "Failed to start libinput backend");
+		wlr_backend_destroy(backend);
+		wlr_session_destroy(session);
+		return NULL;
 	}
 
 	int gpus[8];
@@ -126,10 +138,8 @@ struct wlr_backend *wlr_backend_autocreate(struct wl_display *display) {
 
 	if (!primary_drm) {
 		wlr_log(L_ERROR, "Failed to open any DRM device");
-	}
-
-out:
-	if (wlr_multi_is_empty(backend)) {
+		wlr_backend_destroy(libinput);
+		wlr_session_destroy(session);
 		wlr_backend_destroy(backend);
 		return NULL;
 	}