ui: check sensor list size

selfdrive/ui/ui.cc

@@ -212,9 +212,15 @@ static void update_sockets(UIState *s) {
       if (sensor.which() == cereal::SensorEventData::LIGHT) {
         scene.light_sensor = sensor.getLight();
       } else if (!scene.started && sensor.which() == cereal::SensorEventData::ACCELERATION) {
-        scene.accel_sensor = sensor.getAcceleration().getV()[2];
+        auto accel = sensor.getAcceleration().getV();
+        if (accel.totalSize().wordCount){ // TODO: sometimes empty lists are received. Figure out why
+          scene.accel_sensor = accel[2];
+        }
       } else if (!scene.started && sensor.which() == cereal::SensorEventData::GYRO_UNCALIBRATED) {
-        scene.gyro_sensor = sensor.getGyroUncalibrated().getV()[1];
+        auto gyro = sensor.getGyroUncalibrated().getV();
+        if (gyro.totalSize().wordCount){
+          scene.gyro_sensor = gyro[1];
+        }
       }
     }
   }