Force users to give a custom callback in case of exception to avoid r…

…andom crashes

lwt-unix/conduit_lwt_unix.ml

@@ -318,7 +318,7 @@ let serve_with_default_tls ?timeout ?stop ~ctx ~certfile ~keyfile
   | No_tls -> failwith "No SSL or TLS support compiled into Conduit"
 
 let serve ?backlog ?timeout ?stop
-    ?(on_exn=(fun exn -> !Lwt.async_exception_hook exn))
+    ~on_exn
     ~(ctx:ctx) ~(mode:server) callback =
   let callback flow ic oc =
     Lwt.catch

lwt-unix/conduit_lwt_unix.mli

@@ -80,7 +80,7 @@ type tcp_config = [
   | `Socket of Lwt_unix.file_descr sexp_opaque
 ] [@@deriving sexp]
 
-(** Set of supported listening mechanisms that are supported by this module. 
+(** Set of supported listening mechanisms that are supported by this module.
    - [`TLS server_tls_config]: Use OCaml-TLS or OpenSSL (depending on CONDUIT_TLS) to connect
      to the given [host], [ip], [port] tuple via TCP.
    - [`TLS_native _]: Force use of native OCaml TLS stack to connect.
@@ -166,18 +166,18 @@ val init : ?src:string -> ?tls_server_key:tls_server_key -> unit -> ctx io
     via the [ctx] context to the endpoint described by [client] *)
 val connect : ctx:ctx -> client -> (flow * ic * oc) io
 
-(** [serve ?backlog ?timeout ?stop ?on_exn ~ctx ~mode fn]
+(** [serve ?backlog ?timeout ?stop ~on_exn ~ctx ~mode fn]
     establishes a listening connection of type [mode], using the [ctx]
     context.  The [stop] thread will terminate the server if it ever
     becomes determined.  Every connection will be served in a new
     lightweight thread that is invoked via the [fn] callback.  The
     [fn] callback is passed the {!flow} representing the client
     connection and the associated input {!ic} and output {!oc}
     channels. If the callback raises an exception, it is passed to
-    [on_exn] (by default, to !Lwt.async_exception_hook). *)
+    [on_exn]. *)
 val serve :
   ?backlog:int -> ?timeout:int -> ?stop:(unit io) ->
-  ?on_exn:(exn -> unit) -> ctx:ctx -> mode:server ->
+  on_exn:(exn -> unit) -> ctx:ctx -> mode:server ->
   (flow -> ic -> oc -> unit io) -> unit io
 
 (** [set_max_active nconn] sets the maximum number of active connections