protect against nullish render

[JoviDeCroock]

fixes #4277

[coveralls]

coverage: 99.472%. remained the same
when pulling cc7f94c on no-crash-with-null-render
into 238d580 on main.

[github-actions]

Size Change: +7 B (0%)

Total Size: 60.1 kB

Filename	Size	Change
hooks/dist/hooks.js	1.55 kB	+2 B (0%)
hooks/dist/hooks.module.js	1.59 kB	+2 B (0%)
hooks/dist/hooks.umd.js	1.63 kB	+3 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
compat/dist/compat.js	4 kB	0 B
compat/dist/compat.module.js	3.92 kB	0 B
compat/dist/compat.umd.js	4.06 kB	0 B
debug/dist/debug.js	3.52 kB	0 B
debug/dist/debug.module.js	3.52 kB	0 B
debug/dist/debug.umd.js	3.6 kB	0 B
devtools/dist/devtools.js	232 B	0 B
devtools/dist/devtools.module.js	241 B	0 B
devtools/dist/devtools.umd.js	316 B	0 B
dist/preact.js	4.54 kB	0 B
dist/preact.min.js	4.58 kB	0 B
dist/preact.min.module.js	4.58 kB	0 B
dist/preact.min.umd.js	4.61 kB	0 B
dist/preact.module.js	4.57 kB	0 B
dist/preact.umd.js	4.62 kB	0 B
jsx-runtime/dist/jsxRuntime.js	963 B	0 B
jsx-runtime/dist/jsxRuntime.module.js	938 B	0 B
jsx-runtime/dist/jsxRuntime.umd.js	1.04 kB	0 B
test-utils/dist/testUtils.js	453 B	0 B
test-utils/dist/testUtils.module.js	454 B	0 B
test-utils/dist/testUtils.umd.js	536 B	0 B

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