fix(engine): bail retargeting if target is detached

[ekashida]

Details

Return the original target if we are not able to retarget due to DOM mutations.

Does this PR introduce a breaking change?

• Yes
• No

[salesforce-best-lwc-internal]

Benchmark results

Base commit: 633a000 | Target commit: 2965213

lwc-engine-benchmark

table-append-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table/append/1k	duration	165.00 (±4.35 ms)	158.05 (±3.85 ms)	-6.9ms (4.2%) 👍

table-clear-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table/clear/1k	duration	12.95 (±0.65 ms)	12.40 (±0.60 ms)	-0.5ms (4.2%) 👍

table-create-10k	metric	base(633a000)	target(2965213)	trend
benchmark-table/create/10k	duration	944.20 (±9.50 ms)	940.20 (±8.60 ms)	-4.0ms (0.4%) 👌

table-create-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table/create/1k	duration	113.85 (±2.45 ms)	111.20 (±2.20 ms)	-2.6ms (2.3%) 👍

table-update-10th-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table/update-10th/1k	duration	98.30 (±2.05 ms)	86.00 (±1.95 ms)	-12.3ms (12.5%) 👍

tablecmp-append-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-component/append/1k	duration	244.00 (±7.80 ms)	251.00 (±7.90 ms)	+7.0ms (2.9%) 👎

tablecmp-clear-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-component/clear/1k	duration	20.10 (±1.90 ms)	20.60 (±1.65 ms)	+0.5ms (2.5%) 👌

tablecmp-create-10k	metric	base(633a000)	target(2965213)	trend
benchmark-table-component/create/10k	duration	1658.20 (±8.95 ms)	1656.75 (±12.65 ms)	-1.4ms (0.1%) 👌

tablecmp-create-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-component/create/1k	duration	185.70 (±7.00 ms)	186.05 (±4.25 ms)	+0.4ms (0.2%) 👌

tablecmp-update-10th-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-component/update-10th/1k	duration	84.85 (±6.35 ms)	81.95 (±6.20 ms)	-2.9ms (3.4%) 👌

wc-append-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-wc/append/1k	duration	278.70 (±16.05 ms)	271.45 (±18.50 ms)	-7.3ms (2.6%) 👌

wc-clear-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-wc/clear/1k	duration	29.20 (±1.90 ms)	29.95 (±1.80 ms)	+0.8ms (2.6%) 👌

wc-create-10k	metric	base(633a000)	target(2965213)	trend
benchmark-table-wc/create/10k	duration	2145.10 (±12.95 ms)	2145.75 (±12.80 ms)	+0.7ms (0.0%) 👌

wc-create-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-wc/create/1k	duration	225.10 (±4.90 ms)	226.70 (±5.15 ms)	+1.6ms (0.7%) 👌

wc-update-10th-1k	metric	base(633a000)	target(2965213)	trend
benchmark-table-wc/update-10th/1k	duration	85.05 (±5.60 ms)	86.00 (±6.90 ms)	+1.0ms (1.1%) 👌

[ekashida]

No tests because I'm unable to create a test that throws when retargeting detached targets via programmatic interaction, although I'm able to reproduce via manual interaction.

[ekashida]

Related lightning-components change: https://github.com/salesforce/lightning-components/pull/204