Improved error handeling

app/controllers/errors_controller.rb

@@ -1,17 +1,34 @@
 class ErrorsController < ApplicationController
+  layout 'errors'
+
+  rescue_from StandardError, with: :handle_rendering_error
+
   def forbidden
-    render status: :forbidden
+    render_error_page('errors/forbidden', :forbidden, '403 Forbidden')
   end
 
   def not_found
-    render status: :not_found
+    render_error_page('errors/not_found', :not_found, '404 Not Found')
   end
 
   def unacceptable
-    render status: :unprocessable_content
+    render_error_page('errors/unacceptable', :not_acceptable, '406 Not Acceptable')
+  end
+
+  def unprocessable_entity
+    render_error_page('errors/unprocessable_entity', :unprocessable_entity, '422 Unprocessable Entity')
   end
 
   def internal_server_error
-    render status: :internal_server_error
+    render_error_page('errors/internal_server_error', :internal_server_error, '500 Internal Server Error')
+  end
+
+  private
+
+  def render_error_page(template, status, fallback_message)
+    render template: template, status: status
+  rescue StandardError => e
+    Rails.logger.error("Error rendering #{status} page: #{e.message}")
+    render plain: fallback_message, status: status
   end
 end

app/views/errors/unprocessable_entity.html.erb

@@ -0,0 +1,4 @@
+<% content_for :title, "Verzoek niet verwerkt (422) - #{Rails.application.config.x.site_name}" %>
+<h1>Verzoek niet verwerkt <small>(422)</small></h1>
+<p>Je verzoek kon niet worden verwerkt. Dit komt meestal door ongeldige gegevens.</p>
+<p>Controleer je invoer en probeer het opnieuw. Stuur een <%= link_to 'mailtje', "mailto:#{Rails.application.config.x.admin_email}" %> naar de ICT-commissie als dit probleem blijft optreden.</p>

config/routes.rb

@@ -65,6 +65,7 @@
 
   get '/403', to: 'errors#forbidden'
   get '/404', to: 'errors#not_found'
-  get '/422', to: 'errors#unacceptable'
+  get '/406', to: 'errors#unacceptable'
+  get '/422', to: 'errors#unprocessable_entity'
   get '/500', to: 'errors#internal_server_error'
 end