can't copy folder into docker container

I have a local folder called images that contains bunch of folders and files within. When I run the container I get the following error:
the command I execute: docker run -t -i file-uploader -token=abcdefgh

panic: failed Walk: Failed to walk directory: *fs.PathError lstat ./images/: no such file or directory

goroutine 1 [running]:
main.main()
        /src/main.go:57 +0x357

Here is the Dockerfile I created:

FROM golang:1.16
WORKDIR /src
COPY go.sum go.mod ./
RUN go mod download
COPY ./images/ images/
COPY . .
RUN CGO_ENABLED=0 go build -o /bin/app .
ENTRYPOINT ["/bin/app"]

FROM scratch
COPY --from=0 /bin/app /bin/app
ENTRYPOINT ["/bin/app"]

And, here is the code in the program:

var (
    token = flag.String("token", "", "user's token for application")
    rootpath = flag.String("rootpath", "./images/","folder path to be uploaded")
)

func main() {
    flag.Parse()

    if *token == "" {
        log.Fatal(Red + "please provide a client token => -token={$token}")
    }

    tokenSource := oauth2.StaticTokenSource(&oauth2.Token{AccessToken: *token})
    oauthClient := oauth2.NewClient(context.TODO(), tokenSource)
    client := putio.NewClient(oauthClient)

    paths := make(chan string)
    var wg = new(sync.WaitGroup)
    for i := 0; i < 20; i++ {
        wg.Add(1)
        go worker(paths, wg, client)
    }
    if err := filepath.Walk(*rootpath, func(path string, info os.FileInfo, err error) error {
        if err != nil {
            return fmt.Errorf("Failed to walk directory: %T %w", err, err)
        }
        if !info.IsDir() {
            paths <- path
        }
        return nil
    }); err != nil {
        panic(fmt.Errorf("failed Walk: %w", err))
    }
    close(paths)
    wg.Wait()
}
}

If flag is not provided, its default value is the folder itself which is ./images/. When I run this normally like: go run main.go -token="abcde", it works properly. I did some changes on Dockerfile. Some of the changes I made and tried again and again.:

• replacing COPY . . with COPY ./images/ /images. It should automatically creates a folder inside /src like /src/images and get the local folder from host and put into it. It didn’t work.
• I also did try COPY . ., believing that it will copy everything from host into docker container. It didn’t work either.
• I did put 2 COPY command together. Didn’t work.
• COPY . ./ didn’t work either.

My structure of the project is as follows:

/file-uploader-cli
     /images
     Dockerfile
     file-uploader-cli (binary)
     go.mod with go.sum
     main.go

How can I put /images folder into container and run it properly?
Extra question: /images folder is approx. 500 MB or something. Is it a good practice to put that folder into a container?

I guess it is possible to copy a folder like docker cp {$folder_name} ${container_id}:/{$path}, but it must be a running container or something? I did try this using image_id replacing the container_id but I got an error like No such container:path: 12312312312:/.

EDIT:
the problem is the scratch image which was done in order to reduce the size. However, when I delete the scratch thing, the size of the image became 1.1 GB. Any easier or convenient way to utilize the images folder without having too much size?