ensure that we only try to log exceptions when raven is available

app/jobs/unqueue_message_job.rb

@@ -417,7 +417,9 @@ class UnqueueMessageJob < Postal::Job
             e.backtrace.each { |e| log("#{log_prefix} #{e}") }
             queued_message.retry_later
             log "#{log_prefix} Queued message was unlocked"
-            Raven.capture_exception(e, :extra => {:job_id => self.id, :server_id => queued_message.server_id, :message_id => queued_message.message_id})
+            if defined?(Raven)
+              Raven.capture_exception(e, :extra => {:job_id => self.id, :server_id => queued_message.server_id, :message_id => queued_message.message_id})
+            end
             if queued_message.message
               queued_message.message.create_delivery("Error", :details => "An internal error occurred while sending this message. This message will be retried automatically. This this persists, contact support for assistance.", :output => "#{e.class}: #{e.message}", :log_id => "J-#{self.id}")
             end