NoMethodError: You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each
        from /usr/local/lib/ruby/gems/1.8/gems/ar_mailer-1.3.1/lib/action_mailer/ar_mailer.rb:91:in
`perform_delivery_activerecord'
        from /usr/local/lib/ruby/gems/1.8/gems/actionmailer-2.1.2/lib/action_mailer/base.rb:508:in `
__send__'
        from /usr/local/lib/ruby/gems/1.8/gems/actionmailer-2.1.2/lib/action_mailer/base.rb:508:in `
deliver!'
        from /usr/local/lib/ruby/gems/1.8/gems/actionmailer-2.1.2/lib/action_mailer/base.rb:383:in `
method_missing'
        from /var/apps/staging/app/models/user_observer.rb:3:in `after_create'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/observer.rb:171:
in `send'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/observer.rb:171:
in `update'
        from /usr/local/lib/ruby/1.8/observer.rb:185:in `notify_observers'
        from /usr/local/lib/ruby/1.8/observer.rb:184:in `each'
        from /usr/local/lib/ruby/1.8/observer.rb:184:in `notify_observers'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/callbacks.rb:309
:in `notify'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/callbacks.rb:296
:in `callback'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/callbacks.rb:221
:in `create_without_timestamps'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/timestamp.rb:29:
in `create'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/base.rb:2483:in
`create_or_update_without_callbacks'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/callbacks.rb:207
:in `create_or_update'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/base.rb:2211:in
`save_without_validation'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/validations.rb:9
11:in `save_without_dirty'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/dirty.rb:75:in `
save_without_transactions'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/transactions.rb:
106:in `save'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/connection_adapt
ers/abstract/database_statements.rb:66:in `transaction'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/transactions.rb:
79:in `transaction'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/transactions.rb:
98:in `transaction'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/transactions.rb:
106:in `save'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/transactions.rb:
118:in `rollback_active_record_state!'
        from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.1.2/lib/active_record/transactions.rb:
106:in `save'