Language detection defaults to nil (#3666)

* Default to nil for statuses.language

* Language detection defaults to nil instead of instance UI default

app/lib/language_detector.rb

@@ -10,7 +10,7 @@ class LanguageDetector
   end
 
   def to_iso_s
-    detected_language_code || default_locale.to_sym
+    detected_language_code || default_locale
   end
 
   def prepared_text
@@ -43,6 +43,6 @@ class LanguageDetector
   end
 
   def default_locale
-    account&.user_locale || I18n.default_locale
+    account&.user_locale&.to_sym || nil
   end
 end

app/models/status.rb

@@ -20,7 +20,7 @@
 #  reply                  :boolean          default(FALSE)
 #  favourites_count       :integer          default(0), not null
 #  reblogs_count          :integer          default(0), not null
-#  language               :string           default("en"), not null
+#  language               :string
 #  conversation_id        :integer
 #