ElectionProviderMultiPhase.SignedSubmissionsMap fails to decode on block 6348646

[jsdw]

Not enough data to fill buffer.

Using https://github.com/jsdw/polkadot-historic-decoding-example with the following command hits this:

cargo run --release -- decode-storage-items --types ../frame-decode/types/polkadot_types.yaml --spec-versions polkadot_old_spec_changes.json --connections 3 --starting-number 754 --starting-entry ElectionProviderMultiPhase.SignedSubmissionsMap

We can run the JS version of the command (ie in the /js folder in that repo) with:

./index.js decode-storage-items --block 6348646 --entry ElectionProviderMultiPhase.SignedSubmissionsMap

Curiously, offhand it looks like both get to the same decode result, and perhaps both run out of bytes and don't finish in the same way.