Error in non parametric MCAR Test in R (MissMech Package)

I would like to run a non-parametric MCAR test. When running the TestMCARNormality function of the MissMech package, I get the following error "Error in MissMech::TestMCARNormality(df[naVars], del.lesscases = 2) : ".

df <- data.frame(A1 = c(6, 8, NA, 1, 5),
                 A2 = c(NA, NA, 9, 3, 6),
                 A3 = c(9, NA, 1, NA, 4),
                 B1 = c(NA, NA, 9, 3, 6),
                 B2 = c(9, NA, 1, NA, 4),
                 B3 = c(NA, NA, 9, 3, 6)
)

naVars <- c("A1", "A2", "A3", "B1", "B2", "B3")

MissMech::TestMCARNormality(df[naVars], del.lesscases = 2)