Panic in context .Value() When Key Not Found and .engine is nil

[jcburley]

Description

After upgrading to 1.9.0 (from 1.5.0), our test code is now crashing here in context.go line 1216:

	if !c.engine.ContextWithFallback || c.Request == nil || c.Request.Context() == nil {

The (private) variable engine is nil, hence the crash.

How to reproduce

Can't easily boil down our legacy code to a small example.

Expectations

If there's no Value in a context, return nil instead of panicking.

Actual result

Panic:

goroutine 49 [running]:
testing.tRunner.func1.2({0x18df8c0, 0x20f1f00})
	/usr/local/go/src/testing/testing.go:1396 +0x24e
testing.tRunner.func1()
	/usr/local/go/src/testing/testing.go:1399 +0x39f
panic({0x18df8c0, 0x20f1f00})
	/usr/local/go/src/runtime/panic.go:884 +0x212
XXX/gin-gonic/gin.(*Context).Value(0xc0003ba100, {0x1891280?, 0x1b42dd0?})
	XXX/vendor/github.com/gin-gonic/gin/context.go:1216 +0xfa
XXX.GetLoggerFromContext({0x1b4e018, 0xc0003ba100})

Environment

• go version: 1.20 and 1.19.7
• gin version (or commit ref): v1.9.0
• operating system: Darwin amd64

[jcburley]

Note that if I change that one line to this, our tests pass:

if c.engine == nil || !c.engine.ContextWithFallback || c.Request == nil || c.Request.Context() == nil {

[kennburger]

Fix proposed here, but not merged yet: https://github.com/gin-gonic/gin/pull/3512