[draft] potential fix for memory leak

[developit]

Just a thought based on the retaining objects seen in #2336.

Fixing this would be another potential upside we'd gain from moving to a persistent backing tree.

[github-actions[bot]]

Size Change: +18 B (0%)

Total Size: 38.4 kB

Filename	Size	Change
dist/preact.js	3.71 kB	+5 B (0%)
dist/preact.min.js	3.71 kB	+5 B (0%)
dist/preact.module.js	3.73 kB	+5 B (0%)
dist/preact.umd.js	3.77 kB	+3 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
compat/dist/compat.js	3 kB	0 B
compat/dist/compat.module.js	3.03 kB	0 B
compat/dist/compat.umd.js	3.05 kB	0 B
debug/dist/debug.js	3.08 kB	0 B
debug/dist/debug.module.js	3.07 kB	0 B
debug/dist/debug.umd.js	3.15 kB	0 B
devtools/dist/devtools.js	175 B	0 B
devtools/dist/devtools.module.js	185 B	0 B
devtools/dist/devtools.umd.js	252 B	0 B
hooks/dist/hooks.js	1.05 kB	0 B
hooks/dist/hooks.module.js	1.08 kB	0 B
hooks/dist/hooks.umd.js	1.13 kB	0 B
test-utils/dist/testUtils.js	390 B	0 B
test-utils/dist/testUtils.module.js	392 B	0 B
test-utils/dist/testUtils.umd.js	469 B	0 B

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[coveralls]

Coverage remained the same at 99.792% when pulling 9957b3210346ba6545ca7515a86971b8ffc23560 on potential-fix-memory-leak into b03fc6e19b7f543c9700085dd47e6353211a217a on master.

[developit]

@JoviDeCroock perhaps if we null'd the ._hooks reference when unmounting? The demo in the linked issue continually remounts trees, so it's very likely that this leak happens for unmounted components.

[JoviDeCroock]

@developit yes that was my initial suggestion but very hooks specific.... I think we need to clean up our afterPaintEffects on unmount as well