Fix the infinitely looping `Errors` shrinker #319

Job	Run time
build (8.10.7, 3.12.1.0, ubuntu-latest)	3m 13s
cabal-check (9.6.6, 3.10.3.0, ubuntu-latest)	2m 18s
stylish-haskell (9.6.6, 3.12.1.0, ubuntu-latest)	2m 29s
build (8.10.7, 3.12.1.0, windows-latest)	3m 0s
cabal-fmt (9.6.6, 3.12.1.0, ubuntu-latest)	2m 33s
build (8.10.7, 3.12.1.0, macOS-13)	2m 17s
build (9.2.8, 3.12.1.0, ubuntu-latest)	2m 55s
build (9.2.8, 3.12.1.0, windows-latest)	2m 58s
build (9.2.8, 3.12.1.0, macOS-13)	13s
build (9.4.8, 3.12.1.0, ubuntu-latest)	2m 37s
build (9.4.8, 3.12.1.0, windows-latest)	2m 55s
build (9.4.8, 3.12.1.0, macOS-13)	1s
build (9.6.6, 3.12.1.0, ubuntu-latest)	2m 53s
build (9.6.6, 3.12.1.0, windows-latest)	2m 57s
build (9.6.6, 3.12.1.0, macOS-13)	1s
build (9.8.2, 3.12.1.0, ubuntu-latest)	2m 48s
build (9.8.2, 3.12.1.0, windows-latest)	2m 56s
build (9.8.2, 3.12.1.0, macOS-13)	1s
build (9.10.1, 3.12.1.0, ubuntu-latest)	1m 36s
build (9.10.1, 3.12.1.0, windows-latest)	2m 58s
build (9.10.1, 3.12.1.0, macOS-13)	1m 42s
build (9.6.6, 3.12.1.0, ubuntu-latest, no-debug)	2m 55s
	48m 16s

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