the error of run of this project!

when i use this project in ubunt18.04 .l launch the node ,it make the error in the terminal。 but the procedure donot stop.
the error is "[pcl::KdTreeFLANN::setInputCloud] Cannot create a KDTree with an empty input cloud!"
and this error show many times. 
when i make the robot go ahead to make the semantic map. this error show more and the procedure is stop.
can you help me ?thank you.
