make sure to fail setting gamma on disabled outputs

types/wlr_gamma_control_v1.c

@@ -108,6 +108,7 @@ static void gamma_control_handle_set_gamma(struct wl_client *client,
 	wlr_output_set_gamma(gamma_control->output, ramp_size, r, g, b);
 	if (!wlr_output_test(gamma_control->output)) {
 		gamma_control_send_failed(gamma_control);
+		wlr_output_rollback(gamma_control->output);
 		goto error_table;
 	}
 	free(table);

types/wlr_output.c

@@ -551,6 +551,10 @@ static bool output_basic_test(struct wlr_output *output) {
 		wlr_log(WLR_DEBUG, "Tried to enable adaptive sync on a disabled output");
 		return false;
 	}
+	if (!enabled && output->pending.committed & WLR_OUTPUT_STATE_GAMMA_LUT) {
+		wlr_log(WLR_DEBUG, "Tried to set the gamma lut on a disabled output");
+		return false;
+	}
 
 	return true;
 }