'argument is not a matrix' and related bugs

gistfile1.txt

# PART II
library(DiceKriging)

n <- 100
k <- 3

# Design (fit.draws in tune_*_forest)
design <- matrix(runif(n*k), n, k)

# If both 'response' and 'noise.var' are constants,
# we get the 'argument is not a matrix' error
tryCatch(
  DiceKriging::km(design = design,
                  response = rep(1, n),
                  noise.var = rep(1, n)),
  error=function(e) print(e)
)

# If 'response' is constant
# but 'noise.var' is not, 
# then we get a 'leading minor' error
tryCatch(
  DiceKriging::km(design = design,
                  response = rep(1, n),
                  noise.var =  rnorm(n)),
  error=function(e) print(e)
)

# Weirdly:
# If 'response' is not constant
# then we get no error even if
# 'noise.var' is zero (!)
DiceKriging::km(design = design,
                  response = debiased.errors,
                  noise.var = variance.guess)
cat("Look, ma, no error!")