Fix the infinitely looping `Errors` shrinker #320

Job	Run time
stylish-haskell (9.6.6, 3.12.1.0, ubuntu-latest)	54s
cabal-fmt (9.6.6, 3.12.1.0, ubuntu-latest)	53s
cabal-check (9.6.6, 3.10.3.0, ubuntu-latest)	54s
build (8.10.7, 3.12.1.0, ubuntu-latest)	53s
build (8.10.7, 3.12.1.0, windows-latest)	51s
build (8.10.7, 3.12.1.0, macOS-13)	53s
build (9.2.8, 3.12.1.0, ubuntu-latest)	53s
build (9.2.8, 3.12.1.0, windows-latest)	51s
build (9.2.8, 3.12.1.0, macOS-13)	52s
build (9.4.8, 3.12.1.0, ubuntu-latest)	53s
build (9.4.8, 3.12.1.0, windows-latest)	49s
build (9.4.8, 3.12.1.0, macOS-13)	51s
build (9.6.6, 3.12.1.0, ubuntu-latest)	53s
build (9.6.6, 3.12.1.0, windows-latest)	52s
build (9.6.6, 3.12.1.0, macOS-13)	8s
build (9.8.2, 3.12.1.0, ubuntu-latest)	51s
build (9.8.2, 3.12.1.0, windows-latest)	49s
build (9.8.2, 3.12.1.0, macOS-13)	1s
build (9.10.1, 3.12.1.0, ubuntu-latest)	1m 6s
build (9.10.1, 3.12.1.0, windows-latest)	33s
build (9.10.1, 3.12.1.0, macOS-13)	52s
build (9.6.6, 3.12.1.0, ubuntu-latest, no-debug)	53s
	17m 25s

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