這是代碼 config/config.goconst PROJECT_ID = "projectid"var Ctx = context.Background()var DSClient *datastore.Clienttype Logger struct {    Pkg string}func (l *Logger) Error(v ...interface{}) {    log.Print("Error|", l.Pkg, ": ", v)}func (l *Logger) Info(v ...interface{}) {    log.Print("Info|", l.Pkg, ": ", v)}var propFile = "${env}.properties"var Props *properties.Propertiesfunc init(){    Props = properties.MustLoadFile(propFile, properties.UTF8)    DSClient, err := datastore.NewClient(Ctx, PROJECT_ID)    if err != nil {        log.Fatal("Couldn't connect to DataStore: ", err)    }    log.Print("DataStore Client: ", DSClient)}索引/index.go    import (    ...    "github.com/shwetanka19/project/internal/config")    urs := [] user.User{}    q := datastore.NewQuery("users").Filter("email=", greq.Email).Limit(1)    logger.Info("Now Client: ", config.DSClient)    keys, err := config.DSClient.GetAll(config.Ctx, q, &urs)日志DataStore Client: &{0xc000010840 0xc000119d40 projectid}[Now Client:  <nil>]為什么 Client 已經(jīng)初始化了，現(xiàn)在卻是 nil 呢？API 調(diào)用期間會調(diào)用 index.go 中的代碼。而 config 在服務(wù)器啟動時被調(diào)用。