fix(engine): isBeingConstructed flag is not get out of sync

[caridy]

Details

the flag to track the construction process was not restored correctly when the constructor throws and there is no boundary to recovery from such failure. this PR fixes that so it can never be out of sync, using the same trick that we use for isRendering.

Does this PR introduce a breaking change?

• No

[salesforce-best-lwc-internal]

Benchmark results

Base commit: 8bf1dd5 | Target commit: 7efa3cf

lwc-engine-benchmark

table-append-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table/append/1k	duration	151.90 (± 4.90 ms)	149.10 (± 5.30 ms)	1.84% 👌

table-clear-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table/clear/1k	duration	12.15 (± 0.65 ms)	11.90 (± 0.50 ms)	2.06% 👌

table-create-10k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table/create/10k	duration	867.50 (± 7.50 ms)	856.30 (± 4.80 ms)	1.29% 👍

table-create-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table/create/1k	duration	103.10 (± 1.60 ms)	103.60 (± 2.10 ms)	-0.48% 👌

table-update-10th-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table/update-10th/1k	duration	93.80 (± 5.80 ms)	92.60 (± 4.90 ms)	1.28% 👌

tablecmp-append-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table-component/append/1k	duration	253.30 (± 4.60 ms)	263.20 (± 5.30 ms)	-3.91% 👎

tablecmp-clear-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table/clear/1k	duration	32.20 (± 1.20 ms)	33.55 (± 1.80 ms)	-4.19% 👎

tablecmp-create-10k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table-component/create/10k	duration	1721.50 (± 10.00 ms)	1704.50 (± 7.40 ms)	0.99% 👍

tablecmp-create-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table-component/create/1k	duration	199.10 (± 4.80 ms)	197.00 (± 3.30 ms)	1.05% 👍

tablecmp-update-10th-1k	metric	base(8bf1dd5)	target(7efa3cf)	trend
benchmark-table-component/update-10th/1k	duration	74.00 (± 3.20 ms)	76.00 (± 4.20 ms)	-2.70% 👌

[caridy]

@apapko if you want to add a test for this. The scenario is:

• add a error boundary on the parent
• throw in the child's constructor
• in the errorCallback, try to set an attribute on the parent's host (it will throw saying that you're still constructing something.

[davidturissini]

Nice change. Consistent with other approaches

[apapko]

Looks good, but missing tests