Move ellipsis checking

[juliasilge]

Closes #760

This PR moves the ellipsis checking to after the early return when we don't write. The messaging now looks like this:

library(pins)
b <- board_connect()
#> Connecting to Posit Connect 2023.07.0 at <https://colorado.posit.co/rsc>

b |> pin_write(
  1:10, 
  "julia.silge/some-amazing-numbers",
  access_type = "all"
)
#> Guessing `type = 'rds'`
#> ! The hash of pin "julia.silge/some-amazing-numbers" has not changed.
#> • Your pin will not be stored.

^{Created on 2023-08-28 with reprex v2.0.2}

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