🐛 [Bug]: When it starts for a period of time, it indicates that the null pointer is abnormal, and the system is shut down.

[biuaxia]

Bug Description

You need to keep requesting back-end interfaces, and problems will occur after a period of time.

This is the full log:

2023/08/28 16:46:06.223624 bootstrap.go:124: [Warn] {"error":{"code":502,"message":"Bad Gateway"},"errorMsg":"Bad Gateway","exception":{"path":"/","url":"/","ua":"","route":"/","ips":"","host":"","body":"{}","bytesSent":0,"queryParams":"","ip":"192.1.1.45","re
ferer":"","protocol":"http","port":"49794","bytesReceived":0,"resBody":null,"reqHeaders":{},"requestid":null}}
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x1422680]

goroutine 82 [running]:
github.com/gofiber/fiber/v2.(*Ctx).Request(...)
        C:/Users/Administrator/go/pkg/mod/github.com/gofiber/fiber/[email protected]/ctx.go:464
github.com/biuaxia/crawling_FLiNGTrainer/pkg/util.Lang(0xc0000dc000)
        D:/wlm/GolandProjects/crawling_FLiNGTrainer/pkg/util/acceptlanguage_web_util.go:15 +0x120
github.com/biuaxia/crawling_FLiNGTrainer/bootstrap.NewApplication.func5(0x860086?, {0x20bae7c, 0x2})
        D:/wlm/GolandProjects/crawling_FLiNGTrainer/bootstrap/bootstrap.go:193 +0x1d
github.com/gofiber/contrib/fiberi18n.GetMessage({0x1f9b840?, 0xc000377738?})
        C:/Users/Administrator/go/pkg/mod/github.com/gofiber/contrib/[email protected]/i18n.go:105 +0x75
github.com/gofiber/contrib/fiberi18n.MustGetMessage(...)
        C:/Users/Administrator/go/pkg/mod/github.com/gofiber/contrib/[email protected]/i18n.go:85
github.com/biuaxia/crawling_FLiNGTrainer/pkg/i18n.Msg({0x2076328, 0xf})
        D:/wlm/GolandProjects/crawling_FLiNGTrainer/pkg/i18n/i18n.go:10 +0x33
github.com/biuaxia/crawling_FLiNGTrainer/pkg/resp.(*Resp).Build(0xc000377950)
        D:/wlm/GolandProjects/crawling_FLiNGTrainer/pkg/resp/resp.go:75 +0x3b
github.com/biuaxia/crawling_FLiNGTrainer/bootstrap.NewApplication.func3(0xc0001e6c00, {0x2308140, 0xc00028cb70})
        D:/wlm/GolandProjects/crawling_FLiNGTrainer/bootstrap/bootstrap.go:140 +0xd8f
github.com/gofiber/fiber/v2.(*App).ErrorHandler(0xc000280d80, 0xc0001e6c00, {0x2308140, 0xc00028cb70})
        C:/Users/Administrator/go/pkg/mod/github.com/gofiber/fiber/[email protected]/app.go:1054 +0x1ff
github.com/gofiber/fiber/v2.(*App).serverErrorHandler(0xc000280d80, 0xc00070fc20?, {0x23087a0, 0xc000412050})
        C:/Users/Administrator/go/pkg/mod/github.com/gofiber/fiber/[email protected]/app.go:1086 +0x2fb
github.com/valyala/fasthttp.(*Server).writeErrorResponse(0xc000458200?, 0x0, 0xc000252600, {0x0, 0x0}, {0x23087a0?, 0xc000412050?})
        C:/Users/Administrator/go/pkg/mod/github.com/valyala/[email protected]/server.go:2856 +0x57
github.com/valyala/fasthttp.(*Server).serveConn(0xc000458200, {0x230e6f0?, 0xc000384030})
        C:/Users/Administrator/go/pkg/mod/github.com/valyala/[email protected]/server.go:2291 +0x1de5
github.com/valyala/fasthttp.(*workerPool).workerFunc(0xc00045e3c0, 0xc00009c000)
        C:/Users/Administrator/go/pkg/mod/github.com/valyala/[email protected]/workerpool.go:224 +0xa4
github.com/valyala/fasthttp.(*workerPool).getCh.func1()
        C:/Users/Administrator/go/pkg/mod/github.com/valyala/[email protected]/workerpool.go:196 +0x32
created by github.com/valyala/fasthttp.(*workerPool).getCh in goroutine 34
        C:/Users/Administrator/go/pkg/mod/github.com/valyala/[email protected]/workerpool.go:195 +0x1ab

I am using our framework for the first time. Please help me analyze the possible causes of the problem and give me a solution if it is convenient.
Until then, I will try to solve it myself.

How to Reproduce

acceptlanguage_web_util.go:

package util

import (
	"strings"

	"github.com/gofiber/fiber/v2/log"
	"github.com/gofiber/fiber/v2"
)

func Lang(c *fiber.Ctx) string {
	for _, langFinalStr := range []string{
		"lang", "Lang", "LANG",
		"language", "Language", "LANGUAGE",
	} {
		log.Infof("pkg/util/acceptlanguage_web_util.go:15 => c: %#v, request: %#v, langFinalStr: %q", c, c.Request(), langFinalStr)
		langStr := c.Query(langFinalStr)
		if langStr != "" {
			return langStr
		}
	}

	lang := c.Get("Accept-Language")
	if lang != "" {
		var acceptLanguage string
		for _, l := range ParseAcceptLanguage(lang, []string{}) {
			if !strings.Contains(l, "-") {
				acceptLanguage = l
				break
			} else {
				index := strings.Index(l, "-")
				acceptLanguage = l[:index]
			}
		}
		return acceptLanguage
	}
	return "en"
}

Expected Behavior

Normal operation.

Fiber Version

v2.48.0

Code Snippet (optional)

Some of the code is the generation environment, if you need the code, please leave an email, I will send it to you by email.

Checklist:

• I agree to follow Fiber's Code of Conduct.
• I have checked for existing issues that describe my problem prior to opening this one.
• I understand that improperly formatted bug reports may be closed without explanation.

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[ReneWerner87]

panic is happening in the i18n contrib middleware

Duplicate of gofiber/contrib#721

we are on this