It seems that if further down the line after RoutingSlip or DynamicRouter there is a failure in a Route ErrorHandler always will be closed.
This results in a situation where if similar route defined in the same place will fail - there won't be any errorHandler opened and we will get
New exception occurred during processing by the DeadLetterChannel due SendProcessor has not been started: sendTo(mock://result)
Test case which shows the problems in attachment.
Problem started occurring after release 2.18.0 - responsible commit 7c4dd0b4f6ecd4840e4ccdbf1d7c28f2e8cb5691
I was looking for some workarounds/solutions but nothing comes to mind yet so any ideas are welcomed