fix: make RecognizeStream.readableObjectMode always return Boolean

[MasterOdin]

Unifies the return type of RecognizeStream.readableObjectMode to always return Boolean instead of Boolean on Node 12+ and true | undefined for Node 10-. While this is a very slight break in behavior, figured it would be better for v5 than pushing to v4 just to be safe. See #907 for discussion on this, namely the final two comments: #907 (comment) and #907 (comment).

Checklist

• npm test passes (tip: npm run autofix can correct most style issues)

[codecov-io]

Codecov Report

Merging #943 into release-candidate-v5 will decrease coverage by 27.43%.
The diff coverage is 0%.

@@                    Coverage Diff                    @@
##           release-candidate-v5     #943       +/-   ##
=========================================================
- Coverage                 54.36%   26.92%   -27.44%     
=========================================================
  Files                        18       18               
  Lines                      4505     4505               
  Branches                    906      906               
=========================================================
- Hits                       2449     1213     -1236     
- Misses                     2054     3291     +1237     
+ Partials                      2        1        -1

Impacted Files	Coverage Δ
lib/recognize-stream.ts	14.63% <0%> (-50.01%)	⬇️
lib/common.ts	23.07% <0%> (-69.24%)	⬇️
assistant/v2.ts	20.33% <0%> (-62.72%)	⬇️
test/resources/service_error_util.js	20% <0%> (-60%)	⬇️
lib/synthesize-stream.ts	25.86% <0%> (-56.9%)	⬇️
assistant/v1.ts	19.29% <0%> (-56.78%)	⬇️
text-to-speech/v1-generated.ts	47.85% <0%> (-33%)	⬇️
language-translator/v3.ts	30.56% <0%> (-29.26%)	⬇️
tone-analyzer/v3.ts	61.17% <0%> (-28.24%)	⬇️
... and 9 more

---

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[codecov-io]

Codecov Report

Merging #943 into release-candidate-v5 will decrease coverage by 27.43%.
The diff coverage is 0%.

@@                    Coverage Diff                    @@
##           release-candidate-v5     #943       +/-   ##
=========================================================
- Coverage                 54.36%   26.92%   -27.44%     
=========================================================
  Files                        18       18               
  Lines                      4505     4505               
  Branches                    906      906               
=========================================================
- Hits                       2449     1213     -1236     
- Misses                     2054     3291     +1237     
+ Partials                      2        1        -1

Impacted Files	Coverage Δ
lib/recognize-stream.ts	14.63% <0%> (-50.01%)	⬇️
lib/common.ts	23.07% <0%> (-69.24%)	⬇️
assistant/v2.ts	20.33% <0%> (-62.72%)	⬇️
test/resources/service_error_util.js	20% <0%> (-60%)	⬇️
lib/synthesize-stream.ts	25.86% <0%> (-56.9%)	⬇️
assistant/v1.ts	19.29% <0%> (-56.78%)	⬇️
text-to-speech/v1-generated.ts	47.85% <0%> (-33%)	⬇️
language-translator/v3.ts	30.56% <0%> (-29.26%)	⬇️
tone-analyzer/v3.ts	61.17% <0%> (-28.24%)	⬇️
... and 9 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5c11c85...a7aa0e4. Read the comment docs.

[dpopp07]

This looks good, thanks! Just to confirm my understanding, this changes what would be the default behavior for Node 10, but it does not prevent this from functioning with Node 10, right?

[MasterOdin]

Yeah, it just unifies what calling this property in the case that you don't set it to true will return such that node 10 will return the same thing as node 12 (false).

Example code:

const RecognizeStream = require('./lib/recognize-stream.js');

let stream = new RecognizeStream({});
console.log(stream.readableObjectMode);

stream = new RecognizeStream({objectMode: true});
console.log(stream.readableObjectMode);

Environment:

$ node --version
v12.9.0
$ /usr/local/opt/node@10/bin/node --version
v10.16.3

Before patch:

$ node test.js
false
true
$ /usr/local/opt/node@10/bin/node test.js
undefined
true

After patch:

$ node test.js
false
true
$ /usr/local/opt/node@10/bin/node test.js
false
true

Like I mentioned in the PR, this is a fairly inconsequential BC break that it could probably be safe to push to v4, but given that there's an upcoming v5 soon, might as well do it "right" per semver guidelines.