Add status 422 in case of errors only

app/controllers/concerns/notes_actions.rb

@@ -63,7 +63,11 @@ module NotesActions
           json.merge!(note_json(@note))
         end
 
-        render json: json
+        if notes.errors && notes.errors.keys != [:commands_only]
+          render json: json, status: 422
+        else
+          render json: json
+        end
       end
       format.html { redirect_back_or_default }
     end

changelogs/unreleased/http-status-422.yml

+---
+title: Return 422 status code in case of error in submitting comments
+merge_request: 19276
+author:
+type: added