Wasn't able to fix a NoMethodError in Answers#index issue

gistfile1.rb

# I look for solutions for NoMethodError and tried to switch the @answers by @answers
# I tried to redirect the route of answers#index
# The issue happen when I click on "Back" from any page of the answer view, after editing # an "Answer" or when i land on "http://localhost:3000/answers" since the back button 
# redirect me toward this page. I thought the issue could be the name of my path but I
# wasn't able to fix it. I am quite confused that @answer is returned as nil when i click # on back

#========================================
# Error message I get from : http://localhost:3000/answers
#========================================

NoMethodError in Answers#index

Showing /Users/Richardson/rails_projects/WRLY/app/views/answers/index.html.erb where line #11 raised:

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each
Extracted source (around line #11):

8:     <th></th>
9:   </tr>
10: 
11: <% @answers.each do |answer| %>
12:   <tr>
13:     <td><%= answer.location %></td>
14:     <td><%= link_to 'Show', answer %></td>
Rails.root: /Users/Richardson/rails_projects/WRLY

Application Trace | Framework Trace | Full Trace
app/views/answers/index.html.erb:11:in `_app_views_answers_index_html_erb___2623522797869996922_2159166620__2569098313933450991'
app/controllers/answers_controller.rb:8:in `index'

#========================================
#views > answers > index.html.erb
#========================================

<h1>Listing answers</h1>

<table>
  <tr>
    <th>Location</th>
    <th></th>
    <th></th>
    <th></th>
  </tr>

<% @answers.each do |answer| %>
  <tr>
    <td><%= answer.location %></td>
    <td><%= link_to 'Show', answer %></td>
    <td><%= link_to 'Edit', edit_answer_path(answer) %></td>
    <td><%= link_to 'Destroy', answer, :confirm => 'Are you sure?', :method => :delete %></td>
  </tr>
<% end %>
</table>

<br />

<%= link_to 'New Answer', new_answer_path %>

#========================================
# app > controllers > answers_controller.rb
#========================================

 def create

    @micropost = Micropost.find(params[:micropost_id])
    @answer = @micropost.answers.create(params[:answer])

    respond_to do |format|
      if @answer.save
        format.html { redirect_to(micropost_path(@micropost), :notice => 'Answer was successfully created.') }
        format.xml  { render :xml => @micropost, :status => :created, :location => @micropost }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @micropost.errors, :status => :unprocessable_entity }
      end
    end


  end

  def index


    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @answers }
    end
  end

   def show
    @answer = Answer.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @answer }
    end
  end


#========================================
#  config > route.rb
#========================================

WRLY::Application.routes.draw do
  resources :answers

  resources :microposts do
    resources :answers
  end

  root :to => "microposts#index"
end

#========================================
#  Migrations
#========================================


class CreateMicroposts < ActiveRecord::Migration
  def self.up
    create_table :microposts do |t|
      t.string :content

      t.timestamps
    end
  end

  def self.down
    drop_table :microposts
  end
end


class CreateAnswers < ActiveRecord::Migration
  def self.up
    create_table :answers do |t|
      t.string :location
      t.integer :micropost_id
      t.text :body
      t.references :micropost

      t.timestamps
    end


  def self.down
    drop_table :answers

  end
end


class AddMicopostIdToAnswer < ActiveRecord::Migration
  def self.up
    add_column :answers, :micropost_id, :integer
    add_column :answers, :body, :text
  end

  def self.down
    remove_column :answers, :micropost_id
    remove_column :answers, :body
  end
end



class AddmicropostToAnswer < ActiveRecord::Migration
  def self.up
    add_column :answers, :micropost, :reference
  end

  def self.down
    remove_column :answers, :micropost
  end
end