install.rb in xcode-install-0.2.0

- old
+ new

@@ -20,14 +20,16 @@
 				@should_switch = argv.flag?('switch', true)
 				super
 			end
 
 			def validate!
+				return if @version.nil?
 				raise Informative, "Version #{@version} already installed." if @installer.installed?(@version)
 				raise Informative, "Version #{@version} doesn't exist." unless @installer.exist?(@version)
 			end
 
 			def run
+				return if @version.nil?
 				dmgPath = @installer.download(@version)
 				raise Informative, "Failed to download Xcode #{@version}." if dmgPath.nil?
 
 				@installer.install_dmg(dmgPath, "-#{@version.split(' ')[0]}", @should_switch, @should_clean)
 			end