Error accepting friendships

state_machine :state, initial: :pending do
    after_transition on: :accept, do: [:send_acceptance_email, :accept_mutual_friendship!]

    state :requested 

    event :accept do
        transition any => :accepted
    end 
end

def self.request(user1, user2)
    transaction do
        friendship1 = create!(user: user1, friend: user2, state: 'pending')
        friendship2 = create!(user: user2, friend: user1, state: 'requested')

        friendship1.send_request_email
        friendship1
    end
end 

def send_request_email
    UserNotifier.friend_requested(id).deliver
end 

def send_acceptance_email
    UserNotifier.friend_request_accepted(id).deliver
end

def mutual_friendship
    self.class.where({user_id: friend_id, friend_id: user_id}).first
end

def accept_mutual_friendship
    # Grab the mutual friendship and update the state without using the state machine, so as
    # not to invoke callbacks.
    mutual_friendship.update_attribute(:state, 'accepted')
end 

def index
    @user_friendships = current_user.user_friendships.all
end

def accept
    @user_friendship = current_user.user_friendships.find(params[:id])
    if @user_friendship.accept_mutual_friendship?
        flash[:success] = "You are now friends with #{@user_friendship.user.first_name}!"
    else
        flash[:error] = "They think you're a creep."
    end 
    redirect_to user_friendships_path
end 

def new
    if params[:friend_id] #is this rails 4? 
        @friend = User.where(profile_name: params[:friend_id]).first
        #raise ActiveRecord::RecordNotFound if @friend.nil?
        @user_friendship = current_user.user_friendships.new(friend: @friend)
    else
        flash[:error] = "Oh dear ... that person seems to have disappeared. The request failed."
    end

rescue ActiveRecord::RecordNotFound
    render file: 'public/404', status: :not_found
end

def create
    if params[:user_friendship] && params[:user_friendship].has_key?(:friend_id)
        @friend = User.where(profile_name: params[:user_friendship][:friend_id]).first
        @user_friendship = UserFriendship.request(@current_user, @friend)
        if @user_friendship.new_record?
            flash[:error] = "There was a problem creating that friend request."
        else
            flash[:success] = "Friend request sent."
        end 
        redirect_to profile_path(@friend)
    else
        flash[:error] = "Oh dear ... that person seems to have disappeared. The request failed."
        redirect_to root_path
    end
end

def edit
    @user_friendship = current_user.user_friendships.find(params[:id])
    @friend = @user_friendship.friend
end

def friendships_params
  params.permit(:user_id, :friend_id, :users, :friends, :state, :first_name, :user_friendships)
end
#not sure if this params.require is necessary or if it's under user. just need somewhere for the .permit