helpers-misc.md
In tidyselect: Select from a Set of Strings

last_col() checks its inputs

Code
  last_col(Inf, letters[1:3])
Condition
  Error in `last_col()`:
  ! `offset` (Inf) must be smaller than the number of columns (3).
Code
  last_col(3, letters[1:3])
Condition
  Error in `last_col()`:
  ! `offset` (3) must be smaller than the number of columns (3).
Code
  last_col(0, character())
Condition
  Error in `last_col()`:
  ! Can't select last column when input is empty.
Code
  last_col(1:2, letters[1:3])
Condition
  Error in `last_col()`:
  ! `offset` must be a single integer, not an integer vector.