RuntimeError: Unsupported callback newline #26

RuntimeError: Unsupported callback newline
  File "/app/vendor/bundle/ruby/2.3.0/gems/clockwork-2.0.2/lib/clockwork/manager.rb", line 44, in on
  File "/app/vendor/bundle/ruby/2.3.0/gems/clockwork-2.0.2/lib/clockwork.rb", line 38, in on
  ...

RuntimeError: Unsupported callback newline
  File "/app/vendor/bundle/ruby/2.3.0/gems/clockwork-2.0.2/lib/clockwork/manager.rb", line 44, in on
  File "/app/vendor/bundle/ruby/2.3.0/gems/clockwork-2.0.2/lib/clockwork.rb", line 38, in on
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 86, in dispatcher
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 49, in compile
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 7, in block in on_multi
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 7, in each
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 7, in on_multi
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 82, in dispatcher
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 49, in compile
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/mixins/dispatcher.rb", line 45, in call
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/engine.rb", line 50, in block in call
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/engine.rb", line 50, in each
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/engine.rb", line 50, in inject
  File "/app/vendor/bundle/ruby/2.3.0/gems/temple-0.8.0/lib/temple/engine.rb", line 50, in call
  File "/app/vendor/bundle/ruby/2.3.0/gems/haml-5.0.2/lib/haml/temple_engine.rb", line 41, in compile
  File "/app/vendor/bundle/ruby/2.3.0/gems/haml-5.0.2/lib/haml/engine.rb", line 61, in initialize
  File "/app/vendor/bundle/ruby/2.3.0/gems/haml-5.0.2/lib/haml/plugin.rb", line 16, in new
  File "/app/vendor/bundle/ruby/2.3.0/gems/haml-5.0.2/lib/haml/plugin.rb", line 16, in compile
  File "/app/vendor/bundle/ruby/2.3.0/gems/haml-5.0.2/lib/haml/plugin.rb", line 23, in call
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 281, in compile
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 257, in block (2 levels) in compile!
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications.rb", line 168, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 348, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 256, in block in compile!
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 244, in synchronize
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 244, in compile!
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 156, in block in render
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications.rb", line 166, in block in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications/instrumenter.rb", line 21, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications.rb", line 166, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 352, in instrument_render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/template.rb", line 155, in render
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/template_renderer.rb", line 52, in block (2 levels) in render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/abstract_renderer.rb", line 42, in block in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications.rb", line 166, in block in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications/instrumenter.rb", line 21, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.1.3/lib/active_support/notifications.rb", line 166, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/abstract_renderer.rb", line 41, in instrument
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/template_renderer.rb", line 51, in block in render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/template_renderer.rb", line 59, in render_with_layout
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/template_renderer.rb", line 50, in render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/template_renderer.rb", line 14, in render
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/renderer.rb", line 42, in render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/renderer/renderer.rb", line 23, in render
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/rendering.rb", line 103, in _render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-5.1.3/lib/action_controller/metal/streaming.rb", line 217, in _render_template
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionview-5.1.3/lib/action_view/rendering.rb", line 83, in render_to_body
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-5.1.3/lib/action_controller/metal/rendering.rb", line 52, in render_to_body
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-5.1.3/lib/action_controller/metal/renderers.rb", line 141, in render_to_body
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-5.1.3/lib/abstract_controller/rendering.rb", line 46, in render_to_string
  File "/app/vendor/bundle/ruby/2.3.0/gems/actionpack-5.1.3/lib/action_controller/metal/rendering.rb", line 41, in render_to_string
  File "/app/app/models/email_agent/outbound.rb", line 39, in deliver
  File "/app/app/models/delivery_engine.rb", line 13, in block in deliver
  File "/app/vendor/bundle/ruby/2.3.0/gems/retries-0.0.5/lib/retries.rb", line 46, in with_retries
  File "/app/app/models/delivery_engine.rb", line 12, in deliver
  File "/app/app/jobs/delivery_job.rb", line 27, in block in run
  File "/app/vendor/bundle/ruby/2.3.0/gems/activerecord-5.1.3/lib/active_record/connection_adapters/abstract/connection_pool.rb", line 408, in with_connection
  File "/app/app/jobs/delivery_job.rb", line 26, in run