fix event issue when event for left project + project removed

app/models/event.rb

@@ -42,6 +42,14 @@ class Event < ActiveRecord::Base
     push? || issue? || merge_request? || membership_changed?
   end
 
+  def project_name
+    if project
+      project.name
+    else
+      "(deleted)"
+    end
+  end
+
   def push?
     action == self.class::Pushed && valid_push?
   end

app/views/events/_event_membership_changed.html.haml

@@ -2,7 +2,7 @@
 %strong #{event.author_name}
 %span.event_label{class: event.action_name}= event.action_name
 project
-%strong= link_to event.project.name, event.project
+%strong= link_to event.project_name, event.project
 %span.cgray
   = time_ago_in_words(event.created_at)
   ago.