Fix sync peer disconnected when peer has no body

[asdacap]

Fixes issue on kurtosis when peer return empty array on request body.

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[LukaszRozmej]

Shouldn't we validate that all Roots of requested blocks are empty and if not disconnect the peer? So if we are requesting empty or not blocks?

That would check TxRoot, ReceiptsRoot and UncleHash.

Actually, we can do that before sending the request!

[asdacap]

I have no idea. I'm just replicating the logic of MergeBlockDownloader. I guess if all root is empty, then we need to create empty block to replace them? But what if the peer is just waiting to download block from one of it peers?

[LukaszRozmej]

We already have it here:

nethermind/src/Nethermind/Nethermind.Synchronization/Blocks/BlockDownloadContext.cs

Lines 62 to 72 in 82f331a

	if (header.HasBody)
	{
	Blocks[i - 1] = new Block(header);
	_indexMapping.Add(currentBodyIndex, i - 1);
	currentBodyIndex++;
	NonEmptyBlockHashes.Add(header.Hash);
	}
	else
	{
	Blocks[i - 1] = new Block(header, BlockBody.Empty);
	}

so why is that a problem? Some kind of edge case?

[LukaszRozmej]

If all roots are empty don't send the request and don't expect response

[asdacap]

Ok, I think the problem is that the headers returned is 1 instead of 2 which is the minimum.

[LukaszRozmej]

Can you include more robust comment explanation of this scenario?

[asdacap]

What do you have in mind?