I think I spotted a bug in weighted_se.

This works (returns .43)

x  <- c(1,2,3,4)
w <- c(.1, .1, .4, .4)
weighted_se(x, w)

This should return NA, and it does.

x[1] <- NA
weighted_se(x, w)

This shouldn't return NA but it does.
weighted_se(x, w, na.rm=TRUE)

Further, this shouldn't return NA but it does:
weighted_se(x[2:4], w[2:4], na.rm=TRUE)

This, however, works well (returns .36):
weighted_se(x[2:4], w[2:4])

My sessionInfo()

`R version 4.0.0 (2020-04-24)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 18363)

Matrix products: default

locale:
[1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252
[3] LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
[5] LC_TIME=German_Germany.1252

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] diagis_0.1.4

loaded via a namespace (and not attached):
[1] Rcpp_1.0.4.6 lattice_0.20-41 dplyr_1.0.0 crayon_1.3.4
[5] grid_4.0.0 R6_2.4.1 lifecycle_0.2.0 gtable_0.3.0
[9] magrittr_1.5 coda_0.19-3 scales_1.1.1 pillar_1.4.4
[13] ggplot2_3.3.1 rlang_0.4.6 generics_0.0.2 vctrs_0.3.0
[17] ellipsis_0.3.1 tools_4.0.0 glue_1.4.1 purrr_0.3.4
[21] munsell_0.5.0 compiler_4.0.0 pkgconfig_2.0.3 colorspace_1.4-1
[25] tidyselect_1.1.0 gridExtra_2.3 tibble_3.0.1 `

weighted_se gives 0 for all na sample, ought to give na, I guess?!