Facet_grid with empty "data=" in a second geom: empty(data) returns NA and error message is wrong

[alex-l-m]

Someone puts a second facet in a facet_grid, but forgets to add a data argument:

ggplot() + geom_point(aes(x=Sepal.Width, y=Sepal.Length), data=iris) +
  geom_line(aes(x = whatever, y=whatever)) + 
  facet_grid(rows=vars(Species))

Should say something like "whatever not found", but instead you get "Error in if (empty(data)) { : missing value where TRUE/FALSE needed".

[yutannihilation]

Thanks, I found this is a kind of bug. After #3868, the code should fail with the proper error.

devtools::load_all("~/repo/ggplot2")
#> Loading ggplot2

ggplot() + geom_point(aes(x=Sepal.Width, y=Sepal.Length), data=iris) +
  geom_line(aes(x = whatever, y=whatever)) + 
  facet_grid(rows=vars(Species))
#> Error in FUN(X[[i]], ...): object 'whatever' not found