no fallar si no usamos una plantilla

app/controllers/application_controller.rb

@@ -39,7 +39,7 @@ class ApplicationController < ActionController::Base
   end
 
   def find_template(site)
-    id = params[:template_id] || params[:template] || params.require(:post).require(:layout)
+    id = params[:template_id] || params[:template] || params.dig(:post, :layout)
     site.templates.find do |t|
       t.id == id
     end

app/models/post.rb

@@ -63,6 +63,7 @@ class Post
       load_front_matter!
       merge_with_front_matter! front_matter.stringify_keys
     end
+
   end
 
   # Limpiar los errores
@@ -222,6 +223,7 @@ class Post
   end
 
   def template_fields
+    return [] unless template
     @template_fields ||= template.front_matter.reject do |key, _|
       REJECT_FROM_TEMPLATE.include? key
     end.keys
@@ -312,7 +314,9 @@ class Post
 
   # Completa el front_matter a partir de las variables de otro
   def front_matter_from_template
-    return {} unless template
+    # XXX: Llamamos a @template en lugar de template porque sino
+    # entramos en una race condition
+    return {} unless @template
 
     # Convertimos el slug en layout
     ft = template.front_matter.dup