Freezer is failed to freeze data

[rjl493456442]

Sometimes we can have such error log shown Block receipts missing, can't freeze.

[holiman]

 ERROR[11-04|12:35:13.845] Block receipts missing, can't freeze     number=1202001 hash=c4d847…799422 

Relevant block: https://goerli.etherscan.io/block/1202001

No transactions, no uncles, so the receipts should be empty. Still, the freezer should return something, but the fact that the receitps are empty might be important when solving this.

[rjl493456442]

@holiman but even the receipt is nil, the RLP encoded value is [192] which represents an empty list.

So freeze shouldn't fail on empty receipt case.