Handle child exceptions

[jot2re]

Currently exceptions in child-threads are not caught by parent threads. This makes debugging very hard, since child threads are usually responsible for network communication, and thus things can simply stall without knowing what is the cause.
This is in particular an issue when it comes to testing and debugging. Thus the exception handler should be setup in a way where exceptions in child threads get handled, or at a minimum reported.
See for example this page for more detail https://blog.actorsfit.com/a?ID=00600-b7dcac0f-c9d8-42e1-9a6c-f9ddcc740c8f