When we dropped versioning support a new error type was introduced: `invalid-parameters-error` (see https://github.com/BitcoinAndLightningLayerSpecs/lsp/tree/main/LSPS0#-32602-invalid-parameters-error). We currently don't return it, but should, at least if it's not too cumbersome. Other implementors before mentioned that it's not trivial to do with `serde`, if it's too cumbersome we might want to bring it back to the spec group.