lib: check SharedArrayBuffer existence in fast-utf8-stream

[codebytere]

Refs #58897

Fixes the following error:

"Uncaught ReferenceError: SharedArrayBuffer is not defined" 

caused by changes in the above PR that declare const kNil = new Int32Array(new SharedArrayBuffer(4)); when lib/internal/streams/fast-utf8-stream.js is imported and Utf8Stream() is used. This causes an error in any environment missing a SharedArrayBuffer.

I used an alternative sleep implementation in the missing case, but am happy to rework this however is preferred.

[nodejs-github-bot]

Review requested:

• @nodejs/streams

[aduh95]

Is the haveSAB variable useful?

Suggested change

	consthaveSAB=typeofSharedArrayBuffer!=='undefined';
	constkNil=haveSAB ? newInt32Array(newSharedArrayBuffer(4)) : null;
	constkNil=SharedArrayBuffer&&newInt32Array(newSharedArrayBuffer(4));

[codebytere]

@aduh95 we need it below to choose sleep implementation, no?

[aduh95]

We could use kNil for that

[targos]

The suggested code would throw an error if SharedArrayBuffer is not defined.

[aduh95]

It is declared above, it wouldn't throw even if undefined:

node/lib/internal/streams/fast-utf8-stream.js

Line 15 in 6547f21

SharedArrayBuffer,

[mcollina]

lgtm

[codecov]

Codecov Report

❌ Patch coverage is 37.50000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.54%. Comparing base (ddbe136) to head (38de540).
⚠️ Report is 75 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/streams/fast-utf8-stream.js	37.50%	5 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #60453 +/- ## ========================================== - Coverage 88.59% 88.54% -0.05%  ========================================== Files 704 704 Lines 207774 207848 +74 Branches 40035 40045 +10 ========================================== - Hits 184068 184036 -32 - Misses 15748 15850 +102 - Partials 7958 7962 +4 

Files with missing lines	Coverage Δ
lib/internal/streams/fast-utf8-stream.js	73.80% <37.50%> (-0.41%)	⬇️

... and 66 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/70022/