Move by_domain/local interaction check to filter (#39216)

app/controllers/admin/custom_emojis_controller.rb

@@ -5,9 +5,6 @@ module Admin
     def index
       authorize :custom_emoji, :index?
 
-      # If filtering by local emojis, remove by_domain filter.
-      params.delete(:by_domain) if params[:local].present?
-
       # If filtering by domain, ensure remote filter is set.
       if params[:by_domain].present?
         params.delete(:local)

app/models/custom_emoji_filter.rb

@@ -19,7 +19,7 @@ class CustomEmojiFilter
   def results
     scope = CustomEmoji.alphabetic
 
-    params.each do |key, value|
+    relevant_params.each do |key, value|
       next if IGNORED_PARAMS.include?(key.to_s)
 
       scope.merge!(scope_for(key, value)) if value.present?
@@ -30,6 +30,12 @@ class CustomEmojiFilter
 
   private
 
+  def relevant_params
+    params.tap do |args|
+      args.delete(:by_domain) if args[:local].present?
+    end
+  end
+
   def scope_for(key, value)
     case key.to_s
     when 'local'