The plot_cor() function does not work with matrices

[Hanne Oberman]

ggmice::plot_corr(matrix(0, nrow = 10, ncol = 5))
#> Error in stats::cov(data.matrix(data[, vrb]), use = "pairwise.complete.obs"): 'x' is empty

^{Created on 2023-01-26 with reprex v2.0.2}

[Hanne Oberman]

Same with plot_pattern()

plot_pattern(cbind(mice::nhanes$age, NA))

[Hanne Oberman]

@pepijnvink this one is not yet fixed

ggmice::plot_corr(matrix(rnorm(50), nrow = 10, ncol = 5))
#> Error in stats::cov(data.matrix(data[, vrb]), use = "pairwise.complete.obs"): 'x' is empty

^{Created on 2023-06-27 with reprex v2.0.2}