Rails : ActionView::TemplateError (flag after width)

Rails : ActionView::TemplateError (flag after width)

ActionView::TemplateError (flag after width) on line #3 of
vendor/plugins/exception_notification/views/exception_notifier/_environment.rhtml:
1: <% max = @request.env.keys.max { |a,b| a.length <=> b.length } -%>
2: <% @request.env.keys.sort.each do |key| -%>
3: * <%= "%*-s: %s" % [max.length, key,
filter_sensitive_post_data_from_env(key, @request.env[key].to_s.strip)] %>
4: <% end -%>
5:
6: * Process: <%= $$ %>
what? what does this error mean exactly, how does one fix it?