Fixes #3588 - Escalation calculation breaks data privacy ticket deletion.

app/models/ticket/escalation.rb

@@ -56,8 +56,11 @@ returns
     return if callback_loop
 
     # needs to operate on a copy because otherwise caching breaks
-    record_copy = Ticket.find(id)
+    record_copy = Ticket.find_by(id: id)
+    return if !record_copy
+
     record_copy.callback_loop = true
+
     # needs saving explicitly because this is after_commit!
     record_copy.escalation_calculation
   end