tidy.recipe() throws error for zero-step recipes #867
Description
tidy.recipe() should return a zero row tibble for empty recipes instead of throwing an error. This is making step_detect() error when used on empty recipes.
library(recipes)
recipe(~., data = mtcars) %>%
step_center(all_predictors()) %>%
tidy()
#> # A tibble: 1 × 6
#> number operation type trained skip id
#> <int> <chr> <chr> <lgl> <lgl> <chr>
#> 1 1 step center FALSE FALSE center_uXNNk
recipe(~., data = mtcars) %>%
tidy()
#> Error: No steps in recipe.