404 form doesn't save an updated answer

_answer.html.slim

- if answer.persisted?
  = answer.body
  - if current_user&.author_of? answer
    p= link_to "delete answer", answer_path(answer), method: :delete
    p= link_to 'edit', '', class: 'edit-answer-link', data: { answer_id: answer.id }
    p

_answers.html.slim

- @question.answers.each do |answer|
  li id="answer-#{answer.id}"
    - if answer.persisted?
      = answer.body
      - if current_user&.author_of? answer
        p= link_to 'Edit', '', class: 'edit-answer-link', data: { answer_id: answer.id }
        p= link_to "delete answer", answer_path(answer), method: :delete
        p
        = form_for [answer], remote: true, html: { id: "edit-answer-#{answer.id}"} do |f|
          = f.label :body, "Answer"
          = f.text_area :body
          = f.submit 'Save'

answers.coffee

# Place all the behaviors and hooks related to the matching controller here.
# All this logic will automatically be available in application.js.
# You can use CoffeeScript in this file: http://coffeescript.org/

$  ->
  $('.edit-answer-link').click (e) ->
    e.preventDefault();
    $(this).hide();
    answer_id = $(this).data('answerId');
    $('form#edit-answer-' + answer_id).show();

answers.scss

// Place all the styles related to the Answers controller here.
// They will automatically be included in application.css.
// You can use Sass (SCSS) here: http://sass-lang.com/
.edit_answer { display: none; }

answers_controller.rb

class AnswersController < ApplicationController
  before_action :authenticate_user!
  before_action :load_question, only: [:create, :update]
  before_action :load_answer, only: [:edit, :update, :destroy]

  def edit
  end

  def update
    @answer = Answer.find(params[:id])
    @answer.update(answer_params)
    @question = @answer.question
  end

  def create
    @answer = @question.answers.new(answer_params)
    @answer.user = current_user
    @answer.save
  end

  def destroy
    @question = @answer.question
    if current_user.author_of? @answer
      @answer.destroy!
      flash[:notice] = 'Your answer was successfully deleted.'
      redirect_to question_path(@question)
    else
      redirect_to question_path(@question)
    end
  end

  private

  def load_question
    @question = Question.find(params[:question_id])
  end

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

  def answer_params
    params.require(:answer).permit(:body)
  end

end

questions_controller.rb

class QuestionsController < ApplicationController
  before_action :authenticate_user!, only: [:new, :create, :edit, :update, :destroy]
  before_action :load_question, only: [:show, :edit, :update, :destroy]

  def index
    @questions = Question.all
  end

  def show

  end

  def new
    @question = Question.new
  end

  def edit

  end

  def create
    @question = current_user.questions.new(question_params)
    if @question.save
      flash[:notice] = 'Your question was successfully created.'
      redirect_to @question
    else
      render :new
    end
  end

  def update
    if @question.update(question_params)
      redirect_to @question
    else
      render :edit
    end
  end

  def destroy
    if current_user.author_of? @question
      @question.destroy
      flash[:notice] = 'Your question was successfully deleted.'
      redirect_to questions_path
    else
      redirect_to questions_path
    end
  end

  private

  def load_question
    @question = Question.find(params[:id])
  end

  def question_params
    params.require(:question).permit(:title, :body)
  end

end

show.html.slim

h1 = @question.title
p = @question.body

- if current_user&.author_of? @question
  = link_to "delete question", question_path(@question), method: :delete

h2 Answers
.answers
  ul
    = render 'answers/answers'
 
- if user_signed_in?
  .errors
= render 'answers/form'

update.js.erb

<% if @answer.errors.present? %>
    <% @answer.errors.full_messages.each do |message| %>
        $('.answer-errors').html('<%= j message %>');
    <% end %>
<% else %>
    $('#answer<%= @answer.id %>').replaceWith('<%= j render @answer %>');
    $('.answers').html('<%= j render 'answers/answers' %>');
    $('.edit-answer-link').click(function(e) {
        e.preventDefault();
        $(this).hide();
        answer_id = $(this).data('answerId');
        $('form#edit-answer-' + answer_id).show();
    });
<% end %>