unexpected behavior in `f_indexer`

[mlej8]

hi, https://github.com/LaurentMazare/tch-rs/blob/main/src/tensor/index.rs#L336 any thoughts on using f_select here and propagate the error instead of select which panics ?

f_indexer is suppose to return Result<Tensor> but the usage of select means that it will panic instead of propagating an error.

    pub fn select(&self, dim: i64, index: i64) -> Tensor {
        self.f_select(dim, index).unwrap()
    }

why not directly have f_select there and propagate the error upwards

The purpose of having f_i is so that it allows the user to handle the indexing error, but if we panic, then there's no point in having fn f_i

[LaurentMazare]

I think it's just a bug - feel free to make a PR to convert this call to it's f_ variant.