More clear error message when a validator exit was rejected

beacon_chain/conf.nim

@@ -386,7 +386,7 @@ type
 
         rpcUrlForExit* {.
           name: "rpc-url"
-          defaultValue: parseUri("wss://localhost:" & $defaultEth2RpcPort)
+          defaultValue: parseUri("http://localhost:" & $defaultEth2RpcPort)
           desc: "URL of the beacon node JSON-RPC service" }: Uri
 
         exitAtEpoch* {.

beacon_chain/nimbus_beacon_node.nim

@@ -1272,7 +1272,8 @@ proc handleValidatorExitCommand(config: BeaconNodeConf) {.async.} =
           echo "The voluntary exit was not submitted successfully. Please try again."
           quit 1
   except CatchableError as err:
-    fatal "Failed to send the signed exit message to the beacon node RPC"
+    fatal "Failed to send the signed exit message to the beacon node RPC",
+           err = err.msg
     quit 1
 
 programMain: