S3 panic on object creation

[roman-khimov]

Current Behavior

https://http.fs.neo.org/HXSaMJXk2g8C14ht8HSi7BBaiYZ1HeWh2xnWPGQCg4H6/722-1694457866/index.html#suites/b576f3ca5f4b61bb9c08457d0f3c6a57/67a2c94c8b063135/

2023-09-11T19:51:25.428Z	debug	layer/object.go:252	put object	{"reqId": "9deaa8b2-07a2-41ce-8a3b-26588f0e9116", "bucket": "86a17023-150e-4c6d-a49b-1331d0689590", "cid": "9awqoozRE4ETsiJ1uT2YBBbCJn1qiCRZZydAu4t6BwdN", "object": "cc1bd22c-24cd-431f-a9a0-3baa2232bb9e", "oid": "qQaEA5nUX1UtADHBtZp44xuhyhNiMRf8W1suDpUhC4L"}
2023-09-11T19:51:25.440Z	info	http/server.go:3215	http: panic serving 192.168.130.1:57052: runtime error: invalid memory address or nil pointer dereference
goroutine 4743 [running]:
net/http.(*conn).serve.func1()
	net/http/server.go:1854 +0xbf
panic({0xf257e0, 0x1b93fd0})
	runtime/panic.go:890 +0x263
io.copyBuffer({0x7fd5c72fad28, 0xc000112460}, {0x0, 0x0}, {0xc00975e000, 0x4000000, 0x4000000})
	io/io.go:427 +0x197
io.CopyBuffer({0x7fd5c72fad28?, 0xc000112460?}, {0x0?, 0x0?}, {0xc00975e000?, 0x0?, 0x0?})
	io/io.go:400 +0x3c
github.com/nspcc-dev/neofs-s3-gw/internal/neofs.(*NeoFS).CreateObject(0xc0016a7d10, {0x1409ee8, 0xc0009fb890}, {{0xc0006b24d0}, {0x7f, 0x8f, 0xab, 0xed, 0x8c, 0x28, ...}, ...})
	github.com/nspcc-dev/neofs-s3-gw/internal/neofs/neofs.go:281 +0x90c
github.com/nspcc-dev/neofs-s3-gw/api/layer.(*layer).objectPutAndHash(0xc0000ccd90, {0x1409ee8, 0xc0009fb890}, {{0xc0006b24d0}, {0x7f, 0x8f, 0xab, 0xed, 0x8c, 0x28, ...}, ...}, ...)
	github.com/nspcc-dev/neofs-s3-gw/api/layer/object.go:414 +0x168
github.com/nspcc-dev/neofs-s3-gw/api/layer.(*layer).putLockObject(0x1409a50?, {0x1409ee8, 0xc0009fb890}, 0xc000867480, {0xc, 0x66, 0x88, 0x63, 0xbf, 0xc7, ...}, ...)
	github.com/nspcc-dev/neofs-s3-gw/api/layer/system_object.go:129 +0x23e
github.com/nspcc-dev/neofs-s3-gw/api/layer.(*layer).PutLockInfo(0xc0000ccd90, {0x1409ee8, 0xc0009fb890}, 0xc000bdea98)
	github.com/nspcc-dev/neofs-s3-gw/api/layer/system_object.go:71 +0x435
github.com/nspcc-dev/neofs-s3-gw/api/layer.(*layer).PutObject(0xc0000ccd90, {0x1409ee8, 0xc0009fb890}, 0xc000aa6360)
	github.com/nspcc-dev/neofs-s3-gw/api/layer/object.go:275 +0x1129
github.com/nspcc-dev/neofs-s3-gw/api/handler.(*handler).PutObjectHandler(0xc0016fe150, {0x1408a90, 0xc000a85d40}, 0xc00087ba00)
	github.com/nspcc-dev/neofs-s3-gw/api/handler/put.go:249 +0x629
net/http.HandlerFunc.ServeHTTP(...)
	net/http/server.go:2122
github.com/nspcc-dev/neofs-s3-gw/api/metrics.APIStats.func1({0x1408a60?, 0xc0009fb650}, 0xc00087ba00)
	github.com/nspcc-dev/neofs-s3-gw/api/metrics/api.go:122 +0x271
net/http.HandlerFunc.ServeHTTP(...)
	net/http/server.go:2122
github.com/nspcc-dev/neofs-s3-gw/api.(*maxClients).Handle.func1({0x1408a60, 0xc0009fb650}, 0xc00087ba00)
	github.com/nspcc-dev/neofs-s3-gw/api/max_clients.go:51 +0x2f2
net/http.HandlerFunc.ServeHTTP(0xc0016fe150?, {0x1408a60?, 0xc0009fb650?}, 0xc00087ba00?)
	net/http/server.go:2122 +0x2f
github.com/nspcc-dev/neofs-s3-gw/api.appendCORS.func1.1({0x1408a60, 0xc0009fb650}, 0xc0009fc501?)
	github.com/nspcc-dev/neofs-s3-gw/api/router.go:143 +0x6e
net/http.HandlerFunc.ServeHTTP(0x1409ee8?, {0x1408a60?, 0xc0009fb650?}, 0xc0009fc580?)
	net/http/server.go:2122 +0x2f
github.com/nspcc-dev/neofs-s3-gw/api.AttachUserAuth.func1.1({0x1408a60, 0xc0009fb650}, 0xc00087b800)
	github.com/nspcc-dev/neofs-s3-gw/api/user_auth.go:53 +0x634
net/http.HandlerFunc.ServeHTTP(0x1409ee8?, {0x1408a60?, 0xc0009fb650?}, 0x10?)
	net/http/server.go:2122 +0x2f
github.com/nspcc-dev/neofs-s3-gw/api.logErrorResponse.func1.1({0x1409660?, 0xc00083aee0}, 0xc00087b800)
	github.com/nspcc-dev/neofs-s3-gw/api/router.go:155 +0x104
net/http.HandlerFunc.ServeHTTP(0x1409660?, {0x1409660?, 0xc00083aee0?}, 0x2?)
	net/http/server.go:2122 +0x2f
github.com/nspcc-dev/neofs-s3-gw/api.setRequestID.func1({0x1409660, 0xc00083aee0}, 0xc00087b600)
	github.com/nspcc-dev/neofs-s3-gw/api/router.go:135 +0x463
net/http.HandlerFunc.ServeHTTP(0xc00087b500?, {0x1409660?, 0xc00083aee0?}, 0xc000bdf9e8?)
	net/http/server.go:2122 +0x2f
github.com/gorilla/mux.(*Router).ServeHTTP(0xc00047e780, {0x1409660, 0xc00083aee0}, 0xc00087b400)
	github.com/gorilla/[email protected]/mux.go:210 +0x1cf
net/http.serverHandler.ServeHTTP({0x1407370?}, {0x1409660, 0xc00083aee0}, 0xc00087b400)
	net/http/server.go:2936 +0x316
net/http.(*conn).serve(0xc0008afdd0, {0x1409ee8, 0xc005724990})
	net/http/server.go:1995 +0x612
created by net/http.(*Server).Serve
	net/http/server.go:3089 +0x5ed

Expected Behavior

No panic.

Steps to Reproduce

A lot of S3 tests fail this way (but some objects are created).
https://http.fs.neo.org/HXSaMJXk2g8C14ht8HSi7BBaiYZ1HeWh2xnWPGQCg4H6/722-1694457866/index.html#suites/b576f3ca5f4b61bb9c08457d0f3c6a57/67a2c94c8b063135/