undefined method `each' for nil:NilClass outside typical controller

class PostsController < ApplicationController
  before_action :find_post, only: [:edit, :update, :show, :destroy]
  before_action :authenticate_admin!, except: [:index, :show]

  # Index action to render all posts
  def index
    @posts = Post.all.recent
  end

  # Action to create new post
  def new
    @post = Post.new
  end

  # Action to save post in database

  def create

    @post = Post.create!(post_params)
    @post.save!

    respond_to do |format|
      if @post.save
        format.html { redirect_to post_path(@post), notice: 'Post was successfully created.' }
        format.json { render :show, status: :created, location: @post }
      else
        format.html { render :new }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end

  end

  # Action to retrieve post and render edit page
  def edit
    @post = Post.find(params[:id])
  end

  # Action to update post with new information
  def update

    @post = Post.find(params[:id])
    if @post.update(post_params)
      flash[:notice] = "Updated post"
      redirect_to post_path(@post)
    else
      flash[:alert] = "Error updating post!"
      render :edit
    end

  end

  # Action render individual post after retrieval
  def show
    @post = Post.find(params[:id])
  end

  # Action to destroy post from database (perma)

  def destroy

    if @post.destroy
      flash[:notice] = "Post deleted success"
      redirect_to posts_path
    else
      flash[:alert] = "Error update post"
    end

  end

    private

    def post_params
      params.require(:post).permit(:title, :body, :header_image)
    end

    def find_post
      @post = Post.find(params[:id])
    end

end