> <@cubixusin:matrix.org> anyway the problem is in line: `db = Sequel.connect(CONFIG[:database])`
> `Sequel.connect` when i change to `Sequel.sqlite` it works. Its weird for me. Thank for help ;)

sequel's crystal ball is broken :-) It cannot detect that you want 'database' to be an sqlite-DB. Give it a litte help and change 'database' to 'sqlite:database' and you are good to go: 
irb(main):001:0> require 'sequel' => true
> > irb(main):002:0> x=Sequel.connect('blah')
> > Traceback (most recent call last):
> >         7: from /usr/bin/irb:23:in `<main>'
> >         6: from /usr/bin/irb:23:in `load'
> >         5: from /usr/lib64/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
> >         4: from (irb):2
> >         3: from /usr/lib64/ruby/gems/2.7.0/gems/sequel-5.40.0/lib/sequel/core.rb:124:in `connect'
> >         2: from /usr/lib64/ruby/gems/2.7.0/gems/sequel-5.40.0/lib/sequel/database/connecting.rb:36:in `connect'
> >         1: from /usr/lib64/ruby/gems/2.7.0/gems/sequel-5.40.0/lib/sequel/database/connecting.rb:17:in `adapter_class'
> > NoMethodError (undefined method `to_sym' for nil:NilClass)
> > irb(main):003:0> x=Sequel.connect('sqlite:blah')
> > => #<Sequel::SQLite::Database: "sqlite:blah">