`fct_lump_n` loses interlacer class

[khusmann]

library(interlacer)
library(forcats)

foo <- interlaced(c("a", "a", "b", "b", "c", "OMITTED"), na = "OMITTED") |>
  map_value_channel(as.factor)

fct_lump_n(foo, 2, other_level = "OTHER")
#> [1] a     a     b     b     OTHER <NA> 
#> attr(,"na_channel_values")
#> [1] <NA>    <NA>    <NA>    <NA>    <NA>    OMITTED
#> Levels: OMITTED
#> Levels: a b OTHER

^{Created on 2024-08-08 with reprex v2.0.2}

[khusmann]

Ah, it's from fct_lump_n -> lvls_other() -> fct_relevel() -> lvls_reorder() -> refactor(). refactor() overwrites the class attribute

So refactor() is written to preserve all the extended attributes of the original factor, but not extensions of the class? It seems like it'd be better if it also preserved the subclass of the factor as well...