cohttp-eio: Improve error handling in example server

The example was using `~on_error:raise`, which causes the server to
crash if any error occurs handling a connection. This is unlikely to be
what you want. Instead, log the error and continue.

This also now matches the behaviour of the Lwt example, which just logs
errors and continues.

CHANGES.md

@@ -1,5 +1,6 @@
 ## Unreleased
 
+- cohttp-eio: Improve error handling in example server (talex5 #1023)
 - cohttp-eio: Don't blow up `Server.callback` on client disconnections. (mefyl #1015)
 - http: Fix assertion in `Source.to_string_trim` when `pos <> 0` (mefyl #1017)
 

cohttp-eio/examples/server1.ml

@@ -42,6 +42,8 @@ let handler _socket request _body =
         Eio.Flow.string_source text )
   | _ -> (Http.Response.make ~status:`Not_found (), Cohttp_eio.Body.of_string "")
 
+let log_warning ex = Logs.warn (fun f -> f "%a" Eio.Exn.pp ex)
+
 let () =
   let port = ref 8080 in
   Arg.parse
@@ -53,4 +55,4 @@ let () =
     Eio.Net.listen env#net ~sw ~backlog:128 ~reuse_addr:true
       (`Tcp (Eio.Net.Ipaddr.V4.loopback, !port))
   and server = Cohttp_eio.Server.make ~callback:handler () in
-  Cohttp_eio.Server.run socket server ~on_error:raise
+  Cohttp_eio.Server.run socket server ~on_error:log_warning