string sometimes gets to_s in equal while half cooked

during debugger register change or update to be precise.
without the debugger there would be no access to the word
at that point and no need for this hack

lib/register/parfait_adapter.rb

@@ -133,7 +133,8 @@ module Parfait
       string = ""
       index = 1
       while( index <= self.char_length)
-        string += get_char(index).chr
+        char = get_char(index)
+        string += char ? char.chr : "*"
         index = index + 1
       end
       string