Error 500 when proceeding to '/pm' page as logged in user

Pre-conditions:
Login as user

Steps:
1. Open main page
2. Add '/pm' to address in the address bar of your browser
i.e. http://qa.jtalks.org/jcommune/pm or http://javatalks.ru/pm
3. Proceed to entered address

Actual result: Page with error 500 is displayed
Expected result: Redirect to '/inbox' page

It's strange to me that for compose private message user goes to '/pm/new' and for view messages to '/inbox'. I think it would be logical to combine all PM-related pages under '/pm/' address and make '/pm' redirect to '/pm/inbox'.