我正在導入 lambda 服務，如下所示：import (    lambdaservice "github.com/aws/aws-sdk-go/service/lambda")并按如下方式使用它：func InvokeCreateSessionLambda(payload invoketypes.Input) {    l := &lambdaservice.Lambda{}    data, _ := json.Marshal(payload)    input := &lambdaservice.InvokeInput{        Payload:        data,        InvocationType: aws.String("RequestResponse"),        FunctionName:   aws.String("MyValidFunctionARN"),        ClientContext:  aws.String("{\"service\":\"somedata\"}"),    }    err := input.Validate()    fmt.Println(err) // prints  <nil>    r, e := l.Invoke(input) <panic>    fmt.Print(e)    fmt.Print(r)}但l.Invoke(input)對（相關）堆棧跟蹤感到恐慌：runtime error: invalid memory address or nil pointer dereference<skipped some lines>panic(0xac91e0, 0x1214ef0)    /usr/local/go/src/runtime/panic.go:522 +0x1b5test-lambda-go/vendor/github.com/aws/aws-sdk-go/aws/client.(*Client).NewRequest(...)    /home/ayush/projects/gojects/src/test-lambda-go/vendor/github.com/aws/aws-sdk-go/aws/client/client.go:84test-lambda-go/vendor/github.com/aws/aws-sdk-go/service/lambda.(*Lambda).newRequest(0xc000107498, 0xc0001f0680, 0xb22ac0, 0xc0001f0640, 0xb12080, 0xc0001f06c0, 0xc0000e2480)    /home/ayush/projects/gojects/src/test-lambda-go/vendor/github.com/aws/aws-sdk-go/service/lambda/service.go:87 +0x3etest-lambda-go/vendor/github.com/aws/aws-sdk-go/service/lambda.(*Lambda).InvokeRequest(0xc000107498, 0xc0001f0640, 0x6, 0xc0001fa000)    /home/ayush/projects/gojects/src/test-lambda-go/vendor/github.com/aws/aws-sdk-go/service/lambda/api.go:1895 +0x102test-lambda-go/vendor/github.com/aws/aws-sdk-go/service/lambda.(*Lambda).Invoke(0xc000107498, 0xc0001f0640, 0xc0001074c0, 0x1, 0x1)    /home/ayush/projects/gojects/src/test-lambda-go/vendor/github.com/aws/aws-sdk-go/service/lambda/api.go:2017 +0x35知道導致錯誤的原因以及如何解決此問題嗎？