to-do: investigate possibly unreachable LOC in `@std/streams/delimiter-stream`

We need to confirm whether the following LOC are indeed unreachable. If they are, with sufficient validation, they can be removed.
https://github.com/denoland/deno_std/blob/c52c6ee057cfd95ecc7a489dc1d0f99cc1d2e0c6/streams/delimiter_stream.ts#L199
https://github.com/denoland/deno_std/blob/c52c6ee057cfd95ecc7a489dc1d0f99cc1d2e0c6/streams/delimiter_stream.ts#L292