> vars_select(letters, TRUE)
Error: Must subset columns with a valid subscript vector.
x Subscript has the wrong type `logical`.
i It must be numeric or character.

> vars_select(letters, 2.5)
Error: Must subset columns with a valid subscript vector.
x Can't convert from <double> to <integer> due to loss of precision.

> vars_select(letters, structure(1:3, class = "tidysel_foobar"))
Error: Must subset columns with a valid subscript vector.
x Subscript has the wrong type `tidysel_foobar`.
i It must be numeric or character.

