More fuzzing improvements and fix bugs found by them #564

Job	Run time
Coverage preset=rust-coverage	1m 34s
ubuntu-latest, preset=rust-release	1m 27s
Coverage preset=rust-with-sqlite-coverage	1m 35s
ubuntu-latest, preset=rust-with-sqlite-release	1m 30s
Coverage preset=c99-coverage	54s
ubuntu-latest, preset=c99-release	54s
Coverage preset=c99-with-uhash-coverage	1m 9s
ubuntu-latest, preset=c99-with-uhash-release	30s
windows-latest, preset=rust-release	4m 17s
windows-latest, preset=rust-with-sqlite-release	4m 11s
windows-latest, preset=c99-release	1m 44s
windows-latest, preset=c99-with-uhash-release	2m 9s
macos-latest, preset=rust-release	1m 22s
macos-latest, preset=rust-with-sqlite-release	1m 13s
macos-latest, preset=c99-release	34s
macos-latest, preset=c99-with-uhash-release	33s
Final Results	1s
	25m 37s

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