Do not use extra dup on error class.

Author: nashby

lib/simple_form/wrappers/many.rb

@@ -68,7 +68,7 @@ def html_options(options)
 
       def html_classes(input, options)
         css = @defaults[:class].dup
-        css << @defaults[:error_class].dup { input.has_errors? }
+        css << @defaults[:error_class] if input.has_errors?
         css.compact
       end
     end