node crashes if undefined passed to an objectMode readable stream

[75lb]

• Version: v8.1.2
• Platform: Darwin mbp.local 16.6.0 Darwin Kernel Version 16.6.0: Fri Apr 14 16:21:16 PDT 2017; root:xnu-3789.60.24~6/RELEASE_X86_64 x86_64
• Subsystem: Stream

The following code works on node v7 but crashes on v8:

const Transform = require('stream').Transform
const stream = new Transform({ objectMode: true })

function processChunk (chunk) { return undefined }

stream._transform = function (chunk, enc, done) {
  if (chunk) {
    this.push(processChunk(chunk))
  }
  done()
}

stream.end({ something: 'whatever' })

Node crashes if my processChunk function returns undefined (which it always does for the purpose of this test case), any other value works fine. However, the docs say that "For object mode streams, chunk may be any JavaScript value." If this is true, undefined should work fine, no?

[75lb]

this is error when running the above script on node v8.1.2:

$ node tmp/issue.js
_stream_readable.js:218
          Object.getPrototypeOf(chunk) !== Buffer.prototype &&
                 ^

TypeError: Cannot convert undefined or null to object
    at Function.getPrototypeOf (<anonymous>)
    at readableAddChunk (_stream_readable.js:218:18)
    at Transform.Readable.push (_stream_readable.js:197:10)
    at Transform.push (_stream_transform.js:151:32)
    at Transform.stream._transform (/Users/lloydb/Documents/tmp/issue.js:8:10)
    at Transform._read (_stream_transform.js:190:10)
    at Transform._write (_stream_transform.js:178:12)
    at doWrite (_stream_writable.js:371:12)
    at writeOrBuffer (_stream_writable.js:357:5)
    at Transform.Writable.write (_stream_writable.js:274:11)

[gibfahn]

cc/ @nodejs/streams