# 'indicator_array' is not a 2-dimensional object
expect_error(plot_grid(indicator_array = array(1, dim = c(2, 2, 2)),
"'indivator_array' needs to be a 2-dimensional object.")
# 'lower_bds' or 'upper_bds' are not of length 2
"Lengths of inputs 'lower_bds' and 'upper_bds' must both be 2.")
# 'lower_bds' needs to be smaller than 'upper_bds'
"'lower_bds' must be smaller than 'upper_bds' at all entries.")
ind_array <- matrix(c(1, 0, 0, 1), nrow = 2, ncol = 2)
p <- plot_grid(ind_array, lower_bds, upper_bds)

"'indivator_array' needs to be a 2-dimensional object."
"Lengths of inputs 'lower_bds' and 'upper_bds' must both be 2."
"'lower_bds' must be smaller than 'upper_bds' at all entries."