`ggmice::plot_pattern()` produces an error if the data does not contain missings

[Thom Volker]

library(mice)
#> 
#> Attaching package: 'mice'
#> The following object is masked from 'package:stats':
#> 
#>     filter
#> The following objects are masked from 'package:base':
#> 
#>     cbind, rbind
library(ggmice)
#> 
#> Attaching package: 'ggmice'
#> The following objects are masked from 'package:mice':
#> 
#>     bwplot, densityplot, stripplot, xyplot
library(ggplot2)

dat <- mice(boys, m = 1) %>% complete
#> 
#>  iter imp variable
#>   1   1  hgt  wgt  bmi  hc  gen  phb  tv  reg
#>   2   1  hgt  wgt  bmi  hc  gen  phb  tv  reg
#>   3   1  hgt  wgt  bmi  hc  gen  phb  tv  reg
#>   4   1  hgt  wgt  bmi  hc  gen  phb  tv  reg
#>   5   1  hgt  wgt  bmi  hc  gen  phb  tv  reg

plot_pattern(dat)
#>  /\     /\
#> {  `---'  }
#> {  O   O  }
#> ==>  V <==  No need for mice. This data set is completely observed.
#>  \  \|/  /
#>   `-----'
#> Error in `chr_as_locations()`:
#> ! Can't subset columns that don't exist.
#> ✖ Columns `age`, `hgt`, `wgt`, `bmi`, `hc`, etc. don't exist.

^{Created on 2022-07-06 by the reprex package (v2.0.1)}

Not per se a big issue, but a simple message that the data is fully observed would probably suffice, rather than throwing an error.
I might look into it later today or tomorrow, but it's probably easy to fix.

[Hanne Oberman]

Thank you!