Ruby on Rails server cannot connect to mysql

everyone. I am trying to set up rails 3 project with mysql as database on macOS X. However, I receive the next error:

/usr/local/bundle/gems/activerecord-3.2.22.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:68:in connection_url_to_hash': undefined method `sub' for nil:NilClass (NoMethodError)

config/database.yml

default: &default
  adapter: mysql2
  pool: 5
  encoding: utf8
  min_messages: warning
  timeout: 5000
  username: root
  password:
  database: heart_development

Can anyone suggest how to solve this problem?