Values can exist with len 0 but non-nil base.

[jamii]

For example:

package main

import (
    "bytes"
    "fmt"
    "github.com/brimdata/zed"
    "github.com/brimdata/zed/zbuf"
    "github.com/brimdata/zed/zio"
    "github.com/brimdata/zed/zio/zngio"
    //"github.com/brimdata/zed/zcode"
    //"github.com/brimdata/zed/zson"
)

func main() {
    bytesReader := bytes.NewReader([]byte("\x14\x00\x1b\x01\x100"))
    context := zed.NewContext()
    reader := zngio.NewReader(context, bytesReader)
    var a zbuf.Array
    if zio.Copy(&a, reader) != nil {
        panic("")
    }
    values := a.Values()
    fmt.Printf("%v\n", values[0])

    value := zed.NewValue(zed.TypeNet, []byte{})
    fmt.Printf("%v\n", *value)
}

The culprit in the first case is:

https://github.com/brimdata/zed/blob/82786cf9030fd1bfce0cd560b6b550f28c934898//zio/zngio/scanner.go#L308

If you try to eg convert these values to zson then it blows up at:

https://github.com/brimdata/zed/blob/82786cf9030fd1bfce0cd560b6b550f28c934898//primitive.go#L344

Not sure what the preferred fix is here. NewValue could detect zero-length slices. decodeValue could not return zero-length slices. zson could be more robust to zero-length slices. ¯_(ツ)_/¯