Disallow commenting when blocked by the answer's author

app/models/user.rb

@@ -150,6 +150,9 @@ class User < ApplicationRecord
   end
 
   def comment(answer, content)
+    raise Errors::CommentingSelfBlockedOther if self.blocking?(answer.user)
+    raise Errors::CommentingOtherBlockedSelf if answer.user.blocking?(self)
+
     Comment.create!(user: self, answer: answer, content: content)
   end
 

lib/errors.rb

@@ -73,5 +73,11 @@ module Errors
 
   class AnsweringSelfBlockedOther < SelfBlockedOther
   end
+
+  class CommentingSelfBlockedOther < SelfBlockedOther
+  end
+
+  class CommentingOtherBlockedSelf < OtherBlockedSelf
+  end
   # endregion
 end