`InvalidCbor` error when reading blocks from `sanchonet` on `Conway` era

[jpraynaud]

Context & versions

It looks like the blocks produced by the 8.8.0-pre Cardano node on the sanchonet network for the Conway era are not correctly parsed by Pallas 0.23.0

Steps to reproduce

We have tried to parse the blocks from latest immutable files produced on the sanchonet network with pallas-hardano and pallas-traverse:

let chunk = pallas_hardano::storage::immutable::chunk::read_blocks(Path::new("./immutable"), "05110").unwrap();

for block in chunk {
    let block = block.unwrap();
    pallas_traverse::MultiEraBlock::decode(&block).unwrap();
}

The immutable files are available on this Mithril snapshot

Actual behavior

We have received the error:

called `Result::unwrap()` on an `Err` value: InvalidCbor("unexpected type tag at position 864: expected array")

Expected behavior

The code should not have panicked and parsed a valid MultiEraBlock.