The FS docs wrongfully indicated support for passing object with an own
`toString` function property to `FileHandle.prototype.appendFile`,
`FileHandle.prototype.writeFile`, `FileHandle.prototype.write`,
`fsPromises.writeFile`, and `fs.writeSync`. This commit fixes that, and
adds some test to ensure the actual behavior is aligned with the docs.
It also fixes a bug that makes the process crash if a non-buffer object
was passed to `FileHandle.prototype.write`.
Refs: https://github.com/nodejs/node/pull/34993
PR-URL: https://github.com/nodejs/node/pull/41677
Backport-PR-URL: https://github.com/nodejs/node/pull/42631
Refs: https://github.com/nodejs/node/issues/41666
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
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