WireGuard outbound: Fix close closed (#5054)

Fixes https://github.com/XTLS/Xray-core/issues/5053

proxy/wireguard/client.go

@@ -129,7 +129,8 @@ func (h *Handler) processWireGuard(ctx context.Context, dialer internet.Dialer)
 	}
 	defer func() {
 		if err != nil {
-			_ = h.bind.Close()
+			h.bind.Close()
+			h.bind = nil
 		}
 	}()