fix 课堂视频创建

app/services/create_watch_video_service.rb

@@ -52,10 +52,9 @@ class CreateWatchVideoService < ApplicationService
             d.duration = params[:duration]
           end
 
+          watch_course_video.save! unless watch_course_video.persisted?
           watch_video_history = build_video_log(current_time, course_video.video_id, watch_course_video.id)
           watch_video_history.save!
-
-          watch_course_video.save! unless watch_course_video.persisted?
         else
           # 非课堂视频
           video = Video.find(params[:video_id])