NoMethodError: undefined method `fetch' for nil:NilClass with postgres

Hello, first of all thank you for this great gem!

I have recently switched from mysql to postgres in one project and have started to get NoMethodError: undefined methodfetch' for nil:NilClass` error when sidekick (we use it as active job adapter) tries to process the photo in background. (full log). With mysql everything worked fine with same configuration.

rails (4.2.9)
sidekiq (5.0.2)
delayed_paperclip (3.0.1)
paperclip (5.1.0)
pg (0.20.0)

Paperclip.interpolates(:placeholder) do |_attachment, _style|
  ActionController::Base.helpers.asset_path('default_image.png')
end

PAPERCLIP_PHOTOS_STORAGE_OPTS = {
      default_url: ':placeholder',
      path: ':rails_root/public:url',
      url: '/:class/:id/:style/:hash.:extension',
      hash_digest: 'SHA256',
      hash_secret: ENV.fetch('PAPERCLIP_HASHSECRET'),
      convert_options: { all: '-quality 92' }
    }.freeze

model:

has_attached_file :photo, PAPERCLIP_PHOTOS_STORAGE_OPTS.merge(
  styles: {
    large: ['1000x1000>', :jpg],
    medium: ['300x300>', :jpg],
    thumb: ['100x100>', :jpg],
    super_thumb: ['30x30>', :jpg]
  },
  only_process: [:large])
process_in_background :photo, only_process: [:medium, :thumb,
                                             :super_thumb]

validates_attachment_content_type :photo, content_type: [
  'image/jpeg',
  'image/tiff',
  'image/png'
]
validates_attachment_size :photo, less_than: 5.megabytes

Is there any gotchas or maybe I have missed something? Thank you in advance!

jrgifford / delayed_paperclip

NoMethodError: undefined method `fetch' for nil:NilClass with postgres #208