Should lr_get_spec() drop columns outside of `lim` or simply return NA?

[Bisaloo]

library(lightr)

lr_get_spec(system.file("testdata", package = "lightr"), ext = "ttt", lim = c(100, 200))
#> 2 files found; importing spectra:
#> Warning in min(bounds): no non-missing arguments to min; returning Inf
#> Warning in max(bounds): no non-missing arguments to max; returning -Inf
#> Warning in min(bounds): no non-missing arguments to min; returning Inf
#> Warning in max(bounds): no non-missing arguments to max; returning -Inf
#> Warning: File import failed.
#> Check input files and function arguments.
#> NULL

^{Created on 2020-02-16 by the reprex package (v0.3.0)}

Alternative output would be a 101x3 rspec object with c("wl", filenames) as column names and the second and third column filled with NA.