`emplace` is not available for single index updates necessitating the use of `import`

I noticed different behavior between documents().import(, { action: "emplace" }) and documents().upsert(, { action: "emplace"}), with the latter working with the behavior of an upsert instead of update when a partial document is passed.

In src/Typesense/Documents.ts:220, the DocumentWriteParameters action property is overwritten by the Object.assign call, negating the ability to pass an action to the upsert call.

Are all actions valid for the upsert call? Perhaps the line could be changed to

  Object.assign({}, options, { action: options.action ?? "upsert" })

Start in src/Typesense/Documents.ts around line 220 and compare how import and upsert pass DocumentWriteParameters.action. Confirm which actions the upsert call accepts, then verify that an explicitly supplied action is preserved while the default remains upsert; run the relevant project tests to confirm the behavior.