清除空图层

(
   _defaultlayer = layerManager.getLayer 0
  _defaultlayer.current = true

try
( 
 _total_layers = layerManager.count - 1
   _layercount = #()
    _layercount = for i = 1 to _total_layers collect i
   _revlayers = #()
 for i in _layercount.count to 1 by -1 do append _revlayers _layercount[i]

   for j in _revlayers do
   (
        _getlayer = layerManager.getlayer j
      LayerManager.deleteLayerByName _getlayer.name
    )       
)
catch()
)