Fix ub and shrink unsafe blocks #538

Job	Run time
build vcpkg (macos-latest)	3m 26s
build linux pkg-config	1m 20s
build vcpkg (ubuntu-latest)	7m 55s
build bundled (macos-latest)	2m 20s
build vcpkg (windows-latest)	7m 28s
build bundled (ubuntu-latest)	3m 28s
build bundled (windows-latest)	5m 59s
build bundled (--release, macos-latest)	2m 0s
build bundled (--release, ubuntu-latest)	2m 36s
build bundled (--release, windows-latest)	4m 47s
build bundled (static-link, macos-latest)	2m 26s
build bundled (static-link, ubuntu-latest)	2m 33s
build bundled (static-link, windows-latest)	5m 4s
build bundled (static-link, --release, macos-latest)	2m 3s
build bundled (static-link, --release, ubuntu-latest)	2m 57s
build bundled (static-link, --release, windows-latest)	6m 48s
	1h 3m 10s

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