Inconsistent mean() in the presence of missing values

[krlmlr]

library(duckplyr)
#> Loading required package: dplyr
#> ✔ Overwriting dplyr methods with duckplyr methods.
#> ℹ Turn off with `duckplyr::methods_restore()`.

duck_tbl(a = c(1:3, NA)) |>
  summarize(b = mean(a))
#> # A duckplyr data frame: 1 variable
#>       b
#>   <dbl>
#> 1     2

duck_tbl(a = c(1:3, NA)) |>
  df_to_parquet("duck_tbl.parquet")
#> NULL

duck_parquet("duck_tbl.parquet") |>
  summarize(b = mean(a))
#> # A duckplyr data frame: 1 variable
#>       b
#>   <dbl>
#> 1     2

^{Created on 2024-12-18 with reprex v2.1.1}

None of the dplyr downstream dependencies seems to rely on this, though.