tee: use is_ok at fn write_flush

[oech3]

match is difficult to understand

[codspeed-hq]

Merging this PR will degrade performance by 23.82%

❌ 1 regressed benchmark
✅ 308 untouched benchmarks
⏩ 46 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	cp_recursive_deep_tree[(120, 4)]	532.7 KB	699.2 KB	-23.82%

---

_{Comparing oech3:tee-simple (d0c42e7) with main (fe7e262)}

Footnotes

1. 46 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/misc/io-errors. tests/misc/io-errors is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/tail/pid-pipe is no longer failing!
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[xtqqczze]

match is difficult to understand

On the contrary, map_err(...).is_ok() is non-idiomatic use of combinators; the match has clear control flow.

[oech3]

Why is duplicating and manually returning true and false cleaner? I strongly disagree.

[xtqqczze]

Suggested change

	res.map_err(|e| {
	if let Err(e) = process_error(mode, e, writer, &mut self.ignored_errors) {
	aborted.get_or_insert(e);
	}
	}
	})
	.is_ok()
	if let Err(e) = res {
	if let Err(e) = process_error(mode, e, writer, &mut self.ignored_errors) {
	aborted.get_or_insert(e);
	}
	false
	} else {
	true
	}

[oech3]

No. It manually returns true and false instead of reusing bool.