please check this log

[webdev1014]

ActionView::Template::Error (Attempting to generate a URL from non-sanitized request parameters! An attacker can inject malicious data into the generated URL, such as changing the host. Whitelist and sanitize passed parameters to be secure.):
00:26:44 web.1 | 7: %th= tw("attributes.email")
00:26:44 web.1 | 8: - unless @mailing
00:26:44 web.1 | 9: %th= tw("attributes.mailing")
00:26:44 web.1 | 10: %th= smart_listing.sortable tw("logs.processing_at"), :processing_at
00:26:44 web.1 | 11: %th= tw("attributes.status")
00:26:44 web.1 | 12: %th
00:26:44 web.1 | 13: %tbody

I've just set maily_herald.config file as like follow
MailyHerald.setup do |config|
config.context :all_users do |context|
context.scope {User.all}
context.destination = :email
context.attributes do |user|
attribute_group(:user) do
attribute(:name) {user.full_name}
attribute(:email) {user.email}
attribute(:created_at) {user.created_at}
end
end
end

config.list :all_users do |list|
list.context_name = :all_users
end

config.one_time_mailing :welcome do |mailing|
mailing.title = "Welcome"
mailing.list = :all_users
mailing.subject = "Hello {{user.name}}!"
mailing.template = "Nice to have you on board. Cheers!"

mailing.start_at = Proc.new{|user| user.created_at + 5.minutes}
# Alternatively you can use Liquid:
# mailing.start_at = "user.created_at | plus: 5, 'minutes'"

mailing.enable

end
end

Why I got this error?

Please help me!!!!