variable_skeleton() returning parameters with incorrect dimensions/size

[mike-lawrence]

To Reproduce

library(tidyverse)
library(cmdstanr)

cmdstanr::write_stan_file(
	code = "data{ int n; int k; } \n parameters{ matrix[n,k] x ;}"
	, dir = './'
	, basename = 'mod'
)

mod = cmdstan_model(
	'mod.stan'
	, compile_model_methods = T
)

tmp = mod$sample(
	data = lst(n=3,k=4)
	, chains = 1
	, adapt_engaged = 0
	, iter_warmup = 0
	, iter_sampling = 1
)
tmp$variable_skeleton() #

yields:

$x
[1] 0 0 0

Expected behavior
x should be a 3x4 array, or if skeleton is expected to flatten all containers to a vector, a 12 element vector.

CmdStanR version number
0.6.0