One more point

[cyanBone]

What version of Go are you using (go version)?

$ go version
go version go1.15.4 darwin/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN="/Users/cyanbone/Application/go/bin"
GOCACHE="/Users/cyanbone/Library/Caches/go-build"
GOENV="/Users/cyanbone/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/cyanbone/Code/Golang/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/cyanbone/Code/Golang"
GOPRIVATE=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/Users/cyanbone/Application/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/cyanbone/Application/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/cyanbone/Code/Golang/github.com/cyanbone/videopro/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/dq/wdgktl215ssg9_k_b0lf02300000gn/T/go-build266668652=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

What did you expect to see?

type User struct {
	Id       int
	NickName string
}

switch err.(type) {
	case *json.UnmarshalTypeError:
		unmarshalTypeError := err.(*json.UnmarshalTypeError)
		if unmarshalTypeError.Field == "" {
			err = fmt.Errorf("%s 类型错误，期望类型 %s", unmarshalTypeError.Field, "json")
		} else {
			err = fmt.Errorf("%s 类型错误，期望类型 %s", unmarshalTypeError.Field, unmarshalTypeError.Type.String())
		}
	}

json.decode

unmarshalTypeError.Field value is "id."

this "unmarshalTypeError.Field" is "id." One more point. Is this correct?

What did you see instead?

unmarshalTypeError.Field value is "id." => "id"