Block close issue

[SurfingNerd]

Setup

1 Moc + 6 Nodes + 1 RPC Node.
Started with 7, switched contract setting to 4 Validators.
1 Node got flagged as unavailable, because it could not write parts of it's transactions.
This leaves 5 potential validators .
4 Nodes got selected as a pending validator, but they are unable to write there ACKS (reason unknown, not part of this issue)

expected behavor:

All 4 Nodes get flagged as unavailable, leaving 1 available node behind that becomes the one and only pending validator.
The one node that is able to take over, is also a current node.

actual behavior:

The contract call crashes.

[SurfingNerd]

could reproduce the issue with the following setup:
new feature automatic sweet spot targeting is active.
had a testnet running well with 6 nodes for a while.
because of the sweet spot rule, it always just picks 4 random nodes.
i added on purpuse 1 additional node, to have the system switching to 7 nodes,
failing it's part creation - and switching back to a new validator set of 4 / 6 nodes.

The switch to 4 nodes happened as expected,
but the nodes could not write their ACKS.

In this case, the system still would have the ability to fall back to 2 other nodes as Validators,
but instead the "reward" call seems to crash.

logs.zip