Commit fafb5a6

@@ -16,7 +16,7 @@ module Elelem
     def add(role: :user, content: "")
       role = role.to_sym
       raise "unknown role: #{role}" unless ROLES.include?(role)
-      return if content.empty?
+      return if content&.empty?
 
       if @items.last && @items.last[:role] == role
         @items.last[:content] += content