Suivi — Tribune HTTP 500 sur un souci de compte dans la tribune ?

Pas encore creusé (compte fermé ou purgé?):

I, [2016年12月07日T22:25:06.076409 #8739] INFO -- : Completed 500 Internal Server Error in 120ms (ActiveRecord: 0.3ms)
F, [2016年12月07日T22:25:06.080971 #8739] FATAL -- : 
ActionView::Template::Error (undefined method `html_safe' for nil:NilClass):
 1: %p.chat{id: "board-#{board.id}"}
 2: %span{class: "board-left", title: board.user_agent}
 3: %time.norloge{datetime: board.created_at.iso8601}= norloge(board, box)
 4: %b= board.user_link
 5: %span{class: "board-right"}= board.message
 app/models/board.rb:34:in `user_link'
 app/views/boards/_board.html.haml:4:in `_app_views_boards__board_html_haml__3025735561608719691_35983540'
 app/views/boards/_boards.html.haml:6:in `_app_views_boards__boards_html_haml___4517043167309487966_35184960'
 app/views/boards/show.html.haml:19:in `_app_views_boards_show_html_haml___3929912801449370356_34808960'
 app/controllers/boards_controller.rb:12:in `show'