bug(binary): `binary` store does not guarantee a `Buffer` on `get`

[dtfiedler]

Environment:

• NodeJS: 18.17.1
• lmdb: 2.8.5

Example:

// index.mjs
import { open } from 'lmdb';

const lmdb = open({
    path: '/data/lmdb',
    encoding: 'binary',
});

const responseObject = await fetch('https://arweave.net/block/height/800079'); // large JSON object
const bigJsonObject = await responseObject.json();

await lmdb.put('my-buffer', Buffer.from(JSON.stringify(bigJsonObject), 'base64'));

const object = lmdb.get('my-buffer');
console.log(object instanceof Uint8Array); // true
console.log(object instanceof Buffer); // false
const isBuffer = Buffer.isBuffer(object); // false

Expectations:

• When we retrieving an Buffer object via get - a Buffer is always returned; in this example, a Uint8Array is returned causing issues downstreams when working with the response

We believe the reason is due to this line, where Buffers can be casted to Uint8Arrays under the hood.

As a workaround we explicitly check that we are returned a Buffer and if not, create one from the returned object:

const potentialBuffer = lmdb.get(key) 
if (potentialBuffer) {
  return Buffer.from(value.buffer);
}

[kriszyp]

This should be addressed in v2.9, I believe.