Ruby: undefined method `name' for nil:NilClass - ruby-on-rails

Question

I'm trying to install this app on Windows 7 https://github.com/cheezy/puppies.
I am not a developer, I am just following below steps to install it:
Ruby Version ruby 2.2.4p230 (2015-12-16 revision 53155) [i386-mingw32] installed on Windows 7
Steps:
Download zip from above link
Inside puppies-master do bundle update and then bundle install.
Then rails s
Launch localhost:3000
It gave error ruby : unsupported parameters: :order. I fixed it by
changing this line
#puppies = Puppy.paginate :page =>params[:page], :order => 'name', :per_page => 4 to this line
#puppies = Puppy.order(:name).paginate(page: params[:page], per_page: 4)
Error was gone and on localhost:3000 it showed me the app launched
But puppies (data) weren't there so I did
bundle && rake db:create && rake db:migrate and then rake db:seed
Refresh the localhost page and all puppies appeared but after I am not able to complete the transaction and on hitting Complete the adoption button it is giving me an error.
undefined method 'name' for nil:NilClass
If you just type undefined method 'name' for nil:NilClass in SOF you will get so many solutions but it seems different then those, because none worked for me.
This is what log says:
Started GET "/orders/new" for 127.0.0.1 at 2017-07-20 10:10:51
Processing by OrdersController#new as HTML
Cart Load (0.0ms) SELECT "carts".* FROM "carts" WHERE "carts"."id" = ? LIMIT 1 [["id", 1]]
CACHE (0.0ms) SELECT "carts".* FROM "carts" WHERE "carts"."id" = ? LIMIT 1 [["id", 1]]
Completed 500 Internal Server Error in 3ms
NoMethodError (undefined method `name' for nil:NilClass):
app/controllers/orders_controller.rb:23:in `new'
Rendered C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/_trace.erb (2.5ms)
Rendered C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.0ms)
Rendered C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (242.5ms)
Started GET "/orders/new" for 127.0.0.1 at 2017-07-20 11:20:21
Processing by OrdersController#new as HTML
Cart Load (0.0ms) SELECT "carts".* FROM "carts" WHERE "carts"."id" = ? LIMIT 1 [["id", 1]]
CACHE (0.0ms) SELECT "carts".* FROM "carts" WHERE "carts"."id" = ? LIMIT 1 [["id", 1]]
Completed 500 Internal Server Error in 3ms
NoMethodError (undefined method `name' for nil:NilClass):
app/controllers/orders_controller.rb:23:in `new'
Rendered C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.0ms)
Rendered C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (1.0ms)
Rendered C:/RailsInstaller/Ruby2.2.0/lib/ruby/gems/2.2.0/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (252.0ms)
Edit:
orders_controller.rb
class OrdersController < ApplicationController
skip_before_filter :authorize, :only => [:new, :create]
def index
#orders = Order.paginate :page=>params[:page], :order=>'created_at desc',
:per_page => 10
respond_to do |format|
format.html # index.html.erb
end
end
def show
#order = Order.find(params[:id])
respond_to do |format|
format.html # show.html.erb
end
end
def new
#cart = current_cart
if current_cart.adoptions.empty?
redirect_to agency_url, :notice => "Your cart is empty"
return
end
#order = Order.new
respond_to do |format|
format.html # new.html.erb
format.json { render :json => #order }
end
end
def edit
#order = Order.find(params[:id])
end
def create
#order = Order.new(params[:order])
#order.add_adoptions_from_cart(current_cart)
respond_to do |format|
if #order.save
Cart.destroy(session[:cart_id])
session[:cart_id] = nil
format.html { redirect_to(agency_url, :notice => 'Thank you for adopting a puppy!') }
format.json { render :json => #order }
else
format.html { render :action => "new" }
end
end
end
def update
#order = Order.find(params[:id])
respond_to do |format|
if #order.update_attributes(params[:order])
format.html { redirect_to(#order, :notice => 'Order was successfully updated.') }
else
format.html { render :action => "edit" }
end
end
end
def destroy
#order = Order.find(params[:id])
adoption = #order.adoptions.first
adoption.delivered_on = Time.now
adoption.save
respond_to do |format|
format.html { redirect_to(orders_url, :notice => "Please thank #{#order.name} for the order!") }
end
end
end
Edit2:
current_card method --
class ApplicationController < ActionController::Base
before_filter :authorize
protect_from_forgery
private
def current_cart
Cart.find(session[:cart_id])
rescue ActiveRecord::RecordNotFound
cart = Cart.create
session[:cart_id] = cart.id
cart
end
protected
def authorize
unless User.find_by_id(session[:user_id])
redirect_to login_url, :notice => "Please log in"
end
end
end