Fix residual calculation inconsistency between `plotResidualsVsCovari… #1172

Job	Run time
bump-dev-version / detect-changes	17s
bump-dev-version / bump-dev-version	20s
R-CMD-Check / ubuntu-latest (release)	11m 6s
test-coverage / test-coverage	4m 39s
R-CMD-Check / macos-latest (release)	12m 47s
R-CMD-Check / windows-latest (release)	15m 16s
pkgdown / check-changes	-1s
pkgdown / pkgdown	7m 5s
	51m 29s

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