FIX: Username for topic creation is required

app/controllers/admin/embedding_controller.rb

@@ -9,6 +9,10 @@ class Admin::EmbeddingController < Admin::AdminController
   end
 
   def update
+    if params[:embedding][:embed_by_username].blank?
+      return render_json_error(I18n.t('site_settings.embed_username_required'))
+    end
+
     Embedding.settings.each do |s|
       @embedding.send("#{s}=", params[:embedding][s])
     end

config/locales/server.en.yml

@@ -1195,6 +1195,7 @@ en:
     embed_username_key_from_feed: "Key to pull discourse username from feed."
     embed_truncate: "Truncate the embedded posts."
     embed_post_limit: "Maximum number of posts to embed."
+    embed_username_required: "The username for topic creation is required."
     embed_whitelist_selector: "CSS selector for elements that are allowed in embeds."
     embed_blacklist_selector: "CSS selector for elements that are removed from embeds."
     notify_about_flags_after: "If there are flags that haven't been handled after this many hours, send an email to the contact_email. Set to 0 to disable."