I have the same issue with batch icon:
(I select a folder with only one file)
loading….. but no crash.
Also trying toggle square window gives this message in the console:
Error; #<NoMethodError; private method `split' called for nil;NilClass>
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/JcB_Add_Icon/Add_icon_window.rb;14
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/JcB_Add_Icon/Add_icon_menu.rb;66;in `load'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/JcB_Add_Icon/Add_icon_menu.rb;66
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/JcB_Add_Icon/Add_icon_menu.rb;66;in `call'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/JcB_Add_Icon/Add_icon_menu.rb;66
Safari Version 6.1.5 (8537.77.4)
SU Version 8.0.14345
OSX 10.8.5