select_var needs to exclude vars that aren't present (and warn)

[mdsumner]

Currently we get a heinous error from netcdf:

read_prof <- function(x, grid = "", ...) {
  tidync::tidync(x) %>% tidync::hyper_tibble(...)
}

library(raadfiles)
f <- argo_files()

library(dplyr)
bgc <- read_prof(f$fullname[15000], select_var = c("PRES", "TEMP", "PSAL", "DOXY", "CHLA", "BBP700", "NITRATE"))

(There's no NITRATE in that file ...)

[mdsumner]

Fixed, was bug ridden