Throw errors for set operations #38

Job	Run time
Documentation	2m 30s
Julia 1.8 - ubuntu-latest - x64 - push	1m 58s
Julia 1.8 - ubuntu-latest - x86 - push	2m 26s
Julia 1.8 - macOS-latest - x64 - push	2m 40s
Julia 1.8 - windows-latest - x64 - push	3m 32s
Julia 1.8 - windows-latest - x86 - push	3m 38s
Julia 1 - ubuntu-latest - x64 - push	2m 23s
Julia 1 - ubuntu-latest - x86 - push	2m 38s
Julia 1 - macOS-latest - x64 - push	2m 25s
Julia 1 - windows-latest - x64 - push	2m 55s
Julia 1 - windows-latest - x86 - push	3m 49s
Julia nightly - ubuntu-latest - x64 - push	1m 56s
Julia nightly - ubuntu-latest - x86 - push	2m 10s
Julia nightly - macOS-latest - x64 - push	2m 37s
Julia nightly - windows-latest - x64 - push	3m 1s
Julia nightly - windows-latest - x86 - push	3m 52s
	44m 30s

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