
column not found
================

> mutate_at(tibble(), "test", ~1)
Error: Can't subset columns that don't exist.
x Column `test` doesn't exist.


not summarising grouping variables
==================================

> tbl <- tibble(gr1 = rep(1:2, 4), gr2 = rep(1:2, each = 4), x = 1:8)
> tbl <- group_by(tbl, gr1)
> summarise_at(tbl, vars(gr1), mean)
Error: Can't subset columns that don't exist.
x Column `gr1` doesn't exist.


improper additional arguments
=============================

> mutate_all(mtcars, length, 0, 0)
Error: Problem with `mutate()` input `mpg`.
x 3 arguments passed to 'length' which requires 1
i Input `mpg` is `.Primitive("length")(mpg, 0, 0)`.

> mutate_all(mtcars, mean, na.rm = TRUE, na.rm = TRUE)
Error: Problem with `mutate()` input `mpg`.
x formal argument "na.rm" matched by multiple actual arguments
i Input `mpg` is `(function (x, ...) ...`.

