When I export to a STL file I get this long list of errors. Please someone help me identify the solution.
undefined method `-’ for nil:NilClass
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:226:in `get_vertex_order’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:106:in `write_face_ascii’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:98:in `call’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:98:in `write_face’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:76:in `block in find_faces’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:73:in `each’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:73:in `find_faces’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:80:in `block in find_faces’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:73:in `each’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:73:in `find_faces’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:68:in `export’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:341:in `block in do_options’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/events.rb:82:in `call’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/events.rb:82:in `block in trigger_event’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/events.rb:78:in `each’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/events.rb:78:in `trigger_event’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/window.rb:357:in `event_control_callback’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/window.rb:311:in `callback_handler’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/window.rb:269:in `block in add_callback’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/window.rb:203:in `call’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/window.rb:203:in `show_modal’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/SKUI/window.rb:203:in `show’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:362:in `do_options’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:375:in `main’
C:/Users/RJ/AppData/Roaming/SketchUp/SketchUp 2017/SketchUp/Plugins/sketchup-stl/exporter.rb:395:in `block in module:Exporter’
SketchUp:1:in`call’