fix bug in slot_load and definition

move parfait helper for reuse

lib/risc/instructions/setter.rb

@@ -21,10 +21,9 @@ module Risc
       @register = register
       @array = array
       @index = index
-#      raise "index 0 " if index < 0
-      raise "Not integer or reg #{index}" unless index.is_a?(Numeric) or RegisterValue.look_like_reg(index)
+      raise "Not integer or reg index #{index}" unless index.is_a?(Numeric) or RegisterValue.look_like_reg(index)
       raise "Not register #{register}" unless RegisterValue.look_like_reg(register)
-      raise "Not register #{array}" unless RegisterValue.look_like_reg(array)
+      raise "Not slot/register #{array}" unless RegisterValue.look_like_reg(array)
     end
     attr_accessor :register , :array , :index