Issues when not having any building polygons in domain

[gusbacos]

The script use FUSION PolyClipData to clip in the LiDAR pointcloud. If there is no building polygons within the domain, this will not work. for instance as below:
alg_params = 'C:/FUSION/PolyClipData64.exe /outside /class:2 "' + buildingFootprint + '" "' + workingpath + 'ground.las" "' + outputs['ClipLidardata']['OUTPUT'] + '"'
will not generate a ground.las if no building polygons are found.

Need to make some form of checker to see if buildings exists, and to think of how to deal with the clips if there is no buildings