I try to insert email template in email in lightning experience but get internal error when modal window "Insert Email Template" opens. On classic everything works fine. It seems something related to permissions because some other users can insert email templates without any errors but I have no idea what I need to add. (Error Id: 1684250086-84181 (-412177269))
A very strange thing but after I gave "read" access on Lead object(which we don't use at all in our project) issue have disappeared.