For release 10.3

[aniketd]

Description

Please include a meaningful description of the PR and link the relevant issues
this PR might resolve.

Also note that:

• New code should be properly tested (even if it does not add new features).
• The fix for a regression should include a test that reproduces said regression.

[lehins]

Some really good progress.
Hopefully my comments unblock you and you can continue progressing further

[lehins]

Try pushing this NonZero type further into SecurityParam

Suggested change

	, securityParameter = nonZeroOr k $ error "The security parameter cannot be zero."
	, securityParameter = k

Because then this invariant will propagate throughout the whole system, instead of having a random error call here.

If we push it far enough it will become a deserializaition failure somewhere in a json or cbor decoder, rather than an exception in pure code.

[jasagredo]

This should probably be in the LedgerDB folder. Also some rewording:

Suggested change

	-- | The "tip" to prune snapshots from.
	--
	-- `SecurityParam` has been updated to use `NonZero` but we need to prune from
	-- @0@ in some cases.
	--
	-- Rather than using a plain `Word64` we use this to be able to distinguish that
	-- we are indeed using
	-- 1. @0@ in places where it is necessary
	-- 2. the security parameter as is, in other places
	data LedgerDBPruneTip = LedgerDBPruneTipZero | LedgerDBPruneTip SecurityParam
	-- | How many ledger states to keep in the LedgerDB after a prune.
	--
	-- Rather than using a plain `Word64` we use this to be able to distinguish that
	-- we are indeed using
	-- 1. @0@ in places where it is necessary, namely when completing the replay of the ImmutableDB blocks as part of opening the ChainDB
	-- 2. the security parameter as is, in other places, note it is a strictly positive value
	data LedgerDBPruneNum = LedgerDBPruneZero | LedgerDBPruneNum SecurityParam

[jasagredo]

Or LedgerDBPruneN or just LedgerDBPrune