Redmine

Hi,

I just discovered that GETting an URL which points to a topic of a forum that does not exist causes an error 500. I could reproduce it by the following steps:

1. Create a new project with forums enabled (optional)
2. Create a new forum
3. Create a new topic, remember the GET url
4. Delete the forum
5. GET the remembered url

The stack trace says:

ERROR MESSAGE:

NoMethodError: undefined method `messages' for nil:NilClass

WHERE:

messages#show

[PROJECT_ROOT]/app/controllers/messages_controller.rb:127

URL:

https://domain.com/redmine/boards/2/topics/55

BACKTRACE:

[PROJECT_ROOT]/app/controllers/messages_controller.rb:127
[GEM_ROOT]/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:462
[GEM_ROOT]/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405
[GEM_ROOT]/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:405
[GEM_ROOT]/gems/activesupport-3.2.12/lib/active_support/callbacks.rb:385

I'm running Redmine 2.2.3.stable.