QUIC sniffer: Fix potential slice panic

[Fangliding]

as said

[awerqo]

Hi!
Thanks a lot for fixing this! 🙏
Not 100% sure, but I may have faced something similar in a real-world scenario.
@Fangliding — based on this log, do you think it was the same issue, or should I investigate further?

xray.service: Failed with result 'exit-code'.
xray.service: Start request repeated too quickly.
Stopped Xray Service.
xray.service: Scheduled restart job, restart counter is at 596.
xray.service: Failed with result 'exit-code'.
xray.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
        github.com/xtls/xray-core/app/dispatcher/default.go:238 +0x405
created by github.com/xtls/xray-core/app/dispatcher.(*DefaultDispatcher).Dispatch in goroutine 124
        github.com/xtls/xray-core/app/dispatcher/default.go:243 +0x11c
github.com/xtls/xray-core/app/dispatcher.(*DefaultDispatcher).Dispatch.func1()
        github.com/xtls/xray-core/app/dispatcher/default.go:360 +0x10f
github.com/xtls/xray-core/app/dispatcher.sniffer({0x14b68d0, 0xc0003639e0}, 0x14b68d0?, 0x0, 0xc0?)
        github.com/xtls/xray-core/app/dispatcher/default.go:350 +0x125
github.com/xtls/xray-core/app/dispatcher.sniffer.func1({0x14b68d0, 0xc0003639e0}, 0xc0003639e0?, 0xc000363b60, 0xc000061e80?, 0>
        github.com/xtls/xray-core/app/dispatcher/sniffer.go:64 +0xdf
github.com/xtls/xray-core/app/dispatcher.(*Sniffer).Sniff(0xc000341a70, {0x14b68d0, 0xc0003639e0}, {0xc0002a6000, 0x9c4, 0x2000>
        github.com/xtls/xray-core/app/dispatcher/sniffer.go:40 +0x25
github.com/xtls/xray-core/app/dispatcher.NewSniffer.func4({0x84e4aa?, 0xc000048100?}, {0xc0002a6000?, 0x80?, 0x11afdc0?})
        github.com/xtls/xray-core/common/protocol/quic/sniff.go:220 +0x1c93
github.com/xtls/xray-core/common/protocol/quic.SniffQUIC({0xc0002a6000, 0x9c4, 0x2000})
goroutine 125 [running]:
panic: runtime error: slice bounds out of range [:2246] with capacity 2048

[Fangliding]

这看起来不像是最新版本的抛出的错误