# changelog
- refactor $k$ and $n$ into variables
- run the decoding FEC test in a loop from $(k - 1) \rho + 1$ to $k \rho$, where $\rho$ is the curve number of bytes per scalar field element, e.g. $31$ for _BLS-12-381_
- add a _NOTE_ about having too few bytes and elements, i.e. below $(k - 1) \rho + 1$
- add a _FIXME_ about having too many bytes and elements, i.e. above $k \rho$

# changelog
- rename `LinalgError` to a more general `KomodoError`
- move `KomodoError` to `error.rs` module
- add a `TooFewShard(usize, usize)` variant

follow up to !3

## description
in !3, to make Clippy happy, `expect` was replace with `unwrap_or_else`, but that suppresses the message of the underlying error, which is not great...

this MR reverts this part of !3 and allows `clippy::expect_fun_call`.

# changelog
- make the FEC decoding test more generic by accepting bytes and encoding by itself
- define a large `BYTES` constant that holds _random_ bytes
- calls the template on a slice of `BYTES`

# changelog
- add a `one_less` argument to `field::merge_elements_into_bytes` to mirror the `one_more` from `field::split_data_into_field_elements`
- add a `linalg` module which defines
  - a `pub LinalgError` enum
  - a `pub(super) Matrix` structure implement for any `ark_ff::Field`, e.g. `<Bls12_381 as Pairing>::ScalarField`
  - `pub(super) Matrix::vandermonde`
  - `pub(super) Matrix::from_vec_vec`
  - `pub(super) Matrix::invert`
  - `pub(super) Matrix::mul`
  - `pub(super) Matrix::transpose`
  - everything is tested extensively
- modify `fec.rs` to use `linalg::Matrix` instead of `reed-solomon-erasure` => tests still pass
- remove the dependency to [`reed-solomon-erasure`](https://github.com/jdetchart/reed-solomon-erasure) completely