Sinatra - ActiveRecord::ConnectionNotEstablished: No connection pool for ActiveRecord::Base

问题

I've only been able to find rails answers to this question. Whenever I run rake db:migrate I am getting the aforementioned error. As far as I am aware, I have setup everything correctly so have no idea what's wrong.

config/environment.rb

ENV['SINATRA_ENV'] ||= "development"

require 'bundler/setup'
Bundler.require(:default, ENV['SINATRA_ENV'])

configure :develpoment do
    set :database, 'sqlite3:db/database.db'
end

require './app'

Rakefile

require "./config/environment"
require "sinatra/activerecord/rake"

来源：https://stackoverflow.com/questions/47401809/sinatra-activerecordconnectionnotestablished-no-connection-pool-for-activer