Unable to retrieve binary documents with TransactionAttemptContext

Description

Fetching binary/plaintext documents via a TransactionAttemptContext seems to fail, and exits without any information. `ctx.get()` for a normal JSON document works, as does fetching the binary doc with `collection.get()`. 

This was discovered when implementing transactions on Ottoman, as we use binary docs for our refdoc implementation. The offending lines are here: https://github.com/couchbaselabs/node-ottoman/pull/758/files#diff-dbfff5681984fd751309a6ef8fbc810eeba678c07dc87f873ff9fec7f18158caR38-R46

Actual Behavior

Using `ctx.get()` with a binary document's ID doesn't return the document, and exits without additional info.

Expected Behavior

Using `ctx.get()` with a binary document's ID should return the document the same way it does for JSON documents.

Evidence

The attached `index.js` file attempts to get three documents (a JSON doc via ctx, a binary doc via collection, and a binary doc via ctx), the first two of which work fine, but it never gets past the last one.

Steps to Reproduce

1. Create binary and JSON documents in `travel-sample._default.users` collection (or adjust the bucket/scope/collection in index.js) and run index.js

2. Observe first two console.log() statements show documents retrieved, but we never make it to the third