message: Fix DimensionsMismatch error message
  The values passed to write! were shifted 1 to the left.
  Fixes
diff: @@ -112,7 +112,7 @@ impl fmt::Display for Error {
  write!(f,
  "The number of RGBA pixels ({:?}) does not match the provided \
  dimensions ({:?}x{:?}).",
  - width, height, pixel_count,
  + pixel_count, width, height,
  )
  }
  Error::OsError(e) => write!(
  