Hanami Model Primary Key Exception

Gemfile

source 'https://rubygems.org'

gem 'sqlite3'
gem 'hanami-model'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    concurrent-ruby (1.0.4)
    dry-configurable (0.5.0)
      concurrent-ruby (~> 1.0)
    dry-container (0.6.0)
      concurrent-ruby (~> 1.0)
      dry-configurable (~> 0.1, >= 0.1.3)
    dry-core (0.2.3)
      concurrent-ruby (~> 1.0)
    dry-equalizer (0.2.0)
    dry-logic (0.4.0)
      dry-container (~> 0.2, >= 0.2.6)
      dry-core (~> 0.1)
      dry-equalizer (~> 0.2)
    dry-types (0.9.3)
      concurrent-ruby (~> 1.0)
      dry-configurable (~> 0.1)
      dry-container (~> 0.3)
      dry-core (~> 0.2, >= 0.2.1)
      dry-equalizer (~> 0.2)
      dry-logic (~> 0.4, >= 0.4.0)
      inflecto (~> 0.0.0, >= 0.0.2)
    hanami-model (0.7.0)
      concurrent-ruby (~> 1.0)
      dry-types (~> 0.9)
      hanami-utils (~> 0.8)
      rom-repository (~> 0.3)
      rom-sql (~> 0.9)
    hanami-utils (0.9.2)
    inflecto (0.0.2)
    rom (2.0.2)
      concurrent-ruby (~> 1.0)
      dry-equalizer (~> 0.2)
      dry-types (~> 0.8)
      rom-mapper (~> 0.4.0)
      rom-support (~> 2.0)
    rom-mapper (0.4.0)
      dry-equalizer (~> 0.2)
      rom-support (~> 2.0.0)
      transproc (~> 0.4.0)
    rom-repository (0.3.1)
      rom (~> 2.0)
      rom-mapper (~> 0.4)
      rom-support (~> 2.0)
    rom-sql (0.9.1)
      dry-core (~> 0.2)
      dry-equalizer (~> 0.2)
      dry-types (~> 0.9)
      rom (~> 2.0)
      rom-support (~> 2.0)
      sequel (~> 4.25)
    rom-support (2.0.0)
      concurrent-ruby (~> 1.0)
      dry-equalizer (~> 0.2)
      transproc (~> 0.4.0)
      wisper (~> 1.6, >= 1.6.0)
    sequel (4.42.0)
    sqlite3 (1.3.13)
    transproc (0.4.1)
    wisper (1.6.1)

PLATFORMS
  ruby

DEPENDENCIES
  hanami-model
  sqlite3

BUNDLED WITH
   1.12.5

main.rb

require 'sequel'
require 'hanami/model'
require 'hanami/model/sql'

DB = Sequel.connect('sqlite://test.db?mode=memory&cache=shared')

DB.create_table? :users do
  String :username, primary_key: true
end

class User < ::Hanami::Entity
  attributes do
    attribute :username, Types::String
  end
end

class UserRepository < ::Hanami::Repository
end

Hanami::Model.configure do
  adapter :sql, 'sqlite://test.db?mode=memory&cache=shared'
end

Hanami::Model.load!

UserRepository.new.create(username: 'foo')

output

$HOME/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/hanami-model-0.7.0/lib/hanami/repository.rb:302:in `rescue in create': comparison of String with 0 failed (Hanami::Model::Error)
        from $HOME/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/hanami-model-0.7.0/lib/hanami/repository.rb:300:in `create'
        from main.rb:26:in `<main>'