删除赋值，未定义的方法`avatar？'为零：NilClass

I am a new student to Ruby on Rails and am currently working on the Deletion HTTP request for my project, a Reddit clone. So far I have implemented Destroy functionality on Topics and Posts successfully. Now that I am working on the deletion of Comments I have hit an error that I am not sure how to deal with.I am a new student to Ruby on Rails and am curr