WireGuard: Improve config error handling; Prevent panic in case of errors during server initialization (#4566)

https://github.com/XTLS/Xray-core/pull/4566#issuecomment-2764779273

proxy/wireguard/gvisortun/tun.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"net/netip"
 	"os"
+	"sync"
 	"syscall"
 
 	"golang.zx2c4.com/wireguard/tun"
@@ -33,6 +34,7 @@ type netTun struct {
 	incomingPacket chan *buffer.View
 	mtu            int
 	hasV4, hasV6   bool
+	closeOnce      sync.Once
 }
 
 type Net netTun
@@ -174,18 +176,15 @@ func (tun *netTun) Flush() error {
 
 // Close implements tun.Device
 func (tun *netTun) Close() error {
-	tun.stack.RemoveNIC(1)
+	tun.closeOnce.Do(func() {
+		tun.stack.RemoveNIC(1)
 
-	if tun.events != nil {
 		close(tun.events)
-	}
 
-	tun.ep.Close()
+		tun.ep.Close()
 
-	if tun.incomingPacket != nil {
 		close(tun.incomingPacket)
-	}
-
+	})
 	return nil
 }