small type stability fix #591

Job	Run time
Julia 1 - macOS-latest -	24m 13s
Julia 1 - ubuntu-latest -	1h 23m 53s
Julia 1 - windows-latest -	1h 32m 36s
Julia lts - macOS-latest -	22m 5s
Julia lts - ubuntu-latest -	1h 11m 6s
Julia lts - windows-latest -	1h 18m 14s
Julia nightly - macOS-latest -	32m 34s
Julia nightly - ubuntu-latest -	49m 17s
Julia nightly - windows-latest -	53m 32s
	8h 27m 30s

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