From 7d1cba99c5a483a5c2210455a13f5b7150ce6568 Mon Sep 17 00:00:00 2001
From: Howard Wu <howardwu20@outlook.com>
Date: Fri, 19 Dec 2025 01:59:57 +0800
Subject: [PATCH] Prevent nil pointer in QUIC Close method

Added a nil check for q.conn in the QUIC Close method to avoid potential nil pointer dereference errors when closing a QUIC connection.

Fixes the panic caused by attempting to close a connection when QUIC connection establishment fails: runtime error: invalid memory address or nil pointer dereference.

Test: Manual

```shell
q @quic://dns.google www.google.com
```
---
 transport/quic.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/transport/quic.go b/transport/quic.go
index d3ba731..d5159d6 100644
--- a/transport/quic.go
+++ b/transport/quic.go
@@ -150,5 +150,8 @@ func addPrefix(b []byte) (m []byte) {
 }
 
 func (q *QUIC) Close() error {
+	if q.conn == nil {
+		return nil
+	}
 	return q.connection().CloseWithError(DoQNoError, "")
 }