Problem with building S matrix for unbalanced hierarchies

[mitchelloharawild]

kd <- structure(list(cat = structure(list(x = c("A", "A", "A", "B", 
                                          NA), agg = c(FALSE, FALSE, FALSE, FALSE, TRUE)), class = c("agg_vec", 
                                                                                                     "vctrs_rcrd", "vctrs_vctr")), subcat = structure(list(x = structure(list(
                                                                                                       x = c(NA, "A1", "A2", NA, NA), agg = c(NA, FALSE, FALSE, 
                                                                                                                                              NA, NA)), class = c("agg_vec", "vctrs_rcrd", "vctrs_vctr"
                                                                                                                                              )), agg = c(TRUE, FALSE, FALSE, TRUE, TRUE)), class = c("agg_vec", 
                                                                                                                                                                                                      "vctrs_rcrd", "vctrs_vctr")), .rows = structure(list(1L, 2L, 
                                                                                                                                                                                                                                                           3L, 4L, 5L), ptype = integer(0), class = c("vctrs_list_of", 
                                                                                                                                                                                                                                                                                                      "vctrs_vctr", "list"))), row.names = c(NA, 5L), class = c("tbl_df", 
                                                                                                                                                                                                                                                                                                                                                                "tbl", "data.frame"), .drop = TRUE)
fabletools:::build_key_data_smat(kd)
#> Error: Internal error in `vec_assign()`: `value` should have been recycled to fit `x`.

^{Created on 2020-08-17 by the reprex package (v0.3.0)}