https://github.com/extendr/extendr/pull/857#pullrequestreview-2502972352 To cover: - taking `T` as an argument input: `impl TryFrom<Robj> for T` - returning T as an arugment input: `impl TryFrom<T> for Robj` - using `T` in tuples `impl TryFrom<&Robj> for T`