[Bug]: Panic in `winSocialisationUpdate()`

Problem encountered

Both the overnight system test run and the overnight market-simulation run have seen core panic:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x16c5395]

goroutine 85031 [running]:
code.vegaprotocol.io/vega/core/settlement.(*Engine).winSocialisationUpdate(0x6466cd8?, 0x0?, 0x0?)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/settlement/engine.go:248 +0x55
code.vegaprotocol.io/vega/core/settlement.(*Engine).SettleMTM(0xc004483d00, {0x4292af8, 0xc00756cb70}, 0xc020386e60, {0xc009843000, 0x4b, 0xc0000b4801?})
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/settlement/engine.go:413 +0x1d5d
code.vegaprotocol.io/vega/core/execution/future.(*Market).confirmMTM(0xc0002d3600, {0x4292af8, 0xc00756cb70}, 0x0)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/execution/future/market.go:2285 +0x207
code.vegaprotocol.io/vega/core/execution/future.(*Market).checkNetwork(0xc0002d3600, {0x4292af8, 0xc00756cb70}, {0xc00f996c00?, 0x1?, 0x0?})
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/execution/future/liquidation.go:105 +0x119e
code.vegaprotocol.io/vega/core/execution/future.(*Market).OnTick(0xc0002d3600, {0x4292af8, 0xc00756cb70}, {0x40?, 0xc00843e4e0?, 0x0?})
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/execution/future/market.go:889 +0x31d
code.vegaprotocol.io/vega/core/execution.(*Engine).OnTick(0xc000035080, {0x4292af8, 0xc00756cb70}, {0x1?, 0x42ad930?, 0x0?})
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/execution/engine.go:1302 +0x4e8
code.vegaprotocol.io/vega/core/vegatime.(*Svc).notify(...)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/vegatime/service.go:107
code.vegaprotocol.io/vega/core/vegatime.(*Svc).SetTimeNow(0xc00067bb00, {0x4292af8, 0xc00756cb70}, {0x40?, 0x6466cd8?, 0x0?})
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/vegatime/service.go:80 +0x24f
code.vegaprotocol.io/vega/core/processor.(*App).OnBeginBlock(0xc000753c00, 0x14ce, {0xc00b8e2300, 0x40}, {0xc008e2fae8?, 0x451712?, 0x0?}, {0x0, 0x0}, {0x6466cd8, ...})
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/processor/abci.go:963 +0x977
code.vegaprotocol.io/vega/core/blockchain/abci.(*App).FinalizeBlock(0xc000e06c00, {0xb8?, 0x37ed1e0?}, 0xc00dec2900)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/blockchain/abci/abci.go:162 +0x43c
code.vegaprotocol.io/vega/cmd/vega/commands/node.(*appW).FinalizeBlock(0xc01b7bf140?, {0x4292a88?, 0xc000076120?}, 0xc008e2fe68?)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/cmd/vega/commands/node/app_wrapper.go:91 +0x2b
code.vegaprotocol.io/vega/core/blockchain/nullchain.(*NullBlockchain).processBlock(0xc0002677a0)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/blockchain/nullchain/nullchain.go:198 +0x4c9
code.vegaprotocol.io/vega/core/blockchain/nullchain.(*NullBlockchain).ForwardTime(0xc0002677a0, 0x77359400)
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/blockchain/nullchain/nullchain.go:275 +0x1e5
code.vegaprotocol.io/vega/core/blockchain/nullchain.(*NullBlockchain).handleForwardTime.func1()
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/blockchain/nullchain/server.go:132 +0x2a
created by code.vegaprotocol.io/vega/core/blockchain/nullchain.(*NullBlockchain).handleForwardTime
    /jenkins/workspace/common/vega-market-sim-reinforcement/extern/vega/core/blockchain/nullchain/server.go:131 +0x24a

This is likely due to the recent code change relating to the new liquidation engine.

Failing overnight system tests: https://jenkins.vega.rocks/blue/organizations/jenkins/common%2Fsystem-tests-nightly/detail/system-tests-nightly/102/tests

There is a high chance that test_position_resolution() was the test that caused it.

Failing market sim case: https://jenkins.vega.rocks/job/common/job/vega-market-sim-reinforcement/116/artifact/network_home/vega-sim-m0fv8j4h/node.err/*view*

Observed behaviour

A panic has occurred during win-socialisation.

Expected behaviour

Win-socialisation occurs without a panic.

Steps to reproduce

1. Submit `xyz` transaction
2. With this payload
3. Query `abc` API
4. Observe the error

Software version

develop

Failing test

test_position_resolution

Jenkins run

https://jenkins.vega.rocks/blue/organizations/jenkins/common%2Fsystem-tests-nightly/detail/system-tests-nightly/102/tests

Configuration used

No response

Relevant log output

No response

A replay file can be found here for a similar market-sim failure, which ran on commit eb2cd3e8996723d37d8fcddabfdfec55e9c8c776 with genesis file:

{
  "genesis_time": "2023-05-09T10:00:00.000000000Z",
  "chain_id": "CUSTOM",
  "initial_height": "0",
  "consensus_params": {
    "block": {
      "max_bytes": "22020096",
      "max_gas": "-1",
      "time_iota_ms": "1"
    },
    "evidence": {
      "max_age_num_blocks": "100000",
      "max_age_duration": "172800000000000",
      "max_bytes": "1048576"
    },
    "validator": {
      "pub_key_types": ["ed25519"]
    },
    "version": {}
  },
  "validators": [
    {
      "address": "7DFD3744A773C166B36F170E4F5EF3E998703F4E",
      "pub_key": {
        "type": "tendermint/PubKeyEd25519",
        "value": "2lPO6I0p5uCBZzeoA2+ECJ2+57LtLVMjXpxH5za9TvE="
      },
      "power": "10",
      "name": ""
    }
  ],
  "app_hash": "",
  "app_state": {
    "assets": {
      "VOTE": {
        "name": "VOTE",
        "symbol": "VOTE",
        "decimals": 5,
        "min_lp_stake": "1",
        "source": {
          "builtin_asset": {
            "max_faucet_amount_mint": "100000000000"
          }
        }
      }
    },
    "validators": {
      "6NemqXSfN4zfZvAQeIANflEFqQ98izX9C0KLI2dITSY=": {
        "id": "c2b0ab69fb1bd19862c04df401920ea62d3e0bce41a50148240f42017824d17a",
        "vega_pub_key": "dfcf0fa8d67cfa11b3a511e320f3c47807a5e0735cc06dd9c2bc00f7ccc67117",
        "vega_pub_key_index": 1,
        "ethereum_address": "0x9e5BEEC6E56B28cCbd02864840B0f1e0125e42Ce",
        "tm_pub_key": "6NemqXSfN4zfZvAQeIANflEFqQ98izX9C0KLI2dITSY=",
        "info_url": "",
        "country": "",
        "name": "",
        "avatar_url": ""
      }
    },
    "network": {
      "replay_attack_threshold": 150
    },
    "network_parameters": {
      "blockchains.ethereumConfig": "{\"network_id\": \"3\", \"chain_id\": \"3\", \"collateral_bridge_contract\": { \"address\": \"0xa6F1E140daC13002Dfd9789D6dBA59117c717D7a\" }, \"confirmations\": 50, \"staking_bridge_contract\": { \"address\": \"0xfce2CC92203A266a9C8e67461ae5067c78f67235\", \"deployment_block_height\": 11001702}, \"multisig_control_contract\": {\"address\": \"0xCF6d41235911184fe6F35D47207813bFF3B91601\", \"deployment_block_height\": 12710009 } }",
      "governance.proposal.asset.maxClose": "8760h0m0s",
      "governance.proposal.asset.maxEnact": "8760h0m0s",
      "governance.proposal.asset.minClose": "1s",
      "governance.proposal.asset.minEnact": "1s",
      "governance.proposal.asset.minProposerBalance": "1",
      "governance.proposal.asset.minVoterBalance": "1",
      "governance.proposal.asset.requiredMajority": "0.66",
      "governance.proposal.asset.requiredParticipation": "0.00001",
      "governance.proposal.freeform.maxClose": "8760h0m0s",
      "governance.proposal.freeform.minClose": "1s",
      "governance.proposal.freeform.minProposerBalance": "1",
      "governance.proposal.freeform.minVoterBalance": "1",
      "governance.proposal.freeform.requiredMajority": "0.66",
      "governance.proposal.freeform.requiredParticipation": "0.00001",
      "governance.proposal.market.maxClose": "8760h0m0s",
      "governance.proposal.market.maxEnact": "8760h0m0s",
      "governance.proposal.market.minClose": "1s",
      "governance.proposal.market.minEnact": "2s",
      "governance.proposal.market.minProposerBalance": "1",
      "governance.proposal.market.minVoterBalance": "1",
      "governance.proposal.market.requiredMajority": "0.66",
      "governance.proposal.market.requiredParticipation": "0.00001",
      "governance.proposal.updateAsset.maxClose": "720h",
      "governance.proposal.updateAsset.maxEnact": "720h",
      "governance.proposal.updateAsset.minClose": "1s",
      "governance.proposal.updateAsset.minEnact": "1s",
      "governance.proposal.updateAsset.minProposerBalance": "1",
      "governance.proposal.updateAsset.minVoterBalance": "1",
      "governance.proposal.updateAsset.requiredMajority": "0.66",
      "governance.proposal.updateAsset.requiredParticipation": "0.09",
      "governance.proposal.updateMarket.maxClose": "8760h0m0s",
      "governance.proposal.updateMarket.maxEnact": "8760h0m0s",
      "governance.proposal.updateMarket.minClose": "1s",
      "governance.proposal.updateMarket.minEnact": "1s",
      "governance.proposal.updateMarket.minProposerBalance": "1",
      "governance.proposal.updateMarket.minProposerEquityLikeShare": "0",
      "governance.proposal.updateMarket.minVoterBalance": "1",
      "governance.proposal.updateMarket.requiredMajority": "0.66",
      "governance.proposal.updateMarket.requiredMajorityLP": "0.66",
      "governance.proposal.updateMarket.requiredParticipation": "0.00001",
      "governance.proposal.updateMarket.requiredParticipationLP": "0",
      "governance.proposal.updateNetParam.maxClose": "8760h0m0s",
      "governance.proposal.updateNetParam.maxEnact": "8760h0m0s",
      "governance.proposal.updateNetParam.minClose": "1s",
      "governance.proposal.updateNetParam.minEnact": "1s",
      "governance.proposal.updateNetParam.minProposerBalance": "1",
      "governance.proposal.updateNetParam.minVoterBalance": "1",
      "governance.proposal.updateNetParam.requiredMajority": "0.5",
      "governance.proposal.updateNetParam.requiredParticipation": "0.00001",
      "governance.proposal.referralProgram.maxClose": "8760h0m0s",
      "governance.proposal.referralProgram.maxEnact": "8760h0m0s",
      "governance.proposal.referralProgram.minClose": "1s",
      "governance.proposal.referralProgram.minEnact": "1s",
      "governance.proposal.referralProgram.minProposerBalance": "1",
      "governance.proposal.referralProgram.minVoterBalance": "1",
      "governance.proposal.referralProgram.requiredMajority": "0.5",
      "governance.proposal.referralProgram.requiredParticipation": "0.00001",
      "governance.proposal.VolumeDiscountProgram.maxClose": "8760h0m0s",
      "governance.proposal.VolumeDiscountProgram.maxEnact": "8760h0m0s",
      "governance.proposal.VolumeDiscountProgram.minClose": "1s",
      "governance.proposal.VolumeDiscountProgram.minEnact": "1s",
      "governance.proposal.VolumeDiscountProgram.minProposerBalance": "1",
      "governance.proposal.VolumeDiscountProgram.minVoterBalance": "1",
      "governance.proposal.VolumeDiscountProgram.requiredMajority": "0.5",
      "governance.proposal.VolumeDiscountProgram.requiredParticipation": "0.00001",
      "governance.proposal.transfer.maxClose": "8760h0m0s",
      "governance.proposal.transfer.maxEnact": "8760h0m0s",
      "governance.proposal.transfer.minClose": "1s",
      "governance.proposal.transfer.minEnact": "1s",
      "governance.proposal.transfer.minProposerBalance": "1",
      "governance.proposal.transfer.minVoterBalance": "1",
      "governance.proposal.transfer.requiredMajority": "0.5",
      "governance.proposal.transfer.requiredParticipation": "0.00001",
      "limits.markets.maxPeggedOrders": "1500",
      "limits.markets.proposePerpetualEnabled": "1",
      "market.auction.maximumDuration": "168h",
      "market.auction.minimumDuration": "1s",
      "market.fee.factors.infrastructureFee": "0.0005",
      "market.fee.factors.makerFee": "0.0002",
      "market.liquidity.bondPenaltyParameter": "0.1",
      "market.liquidity.earlyExitPenalty": "0.1",
      "market.liquidity.maximumLiquidityFeeFactorLevel": "0.03",
      "market.liquidity.minimum.probabilityOfTrading.lpOrders": "1e-6",
      "market.liquidity.probabilityOfTrading.tau.scaling": "10.0",
      "market.liquidity.providersFeeCalculationTimeStep": "1s",
      "market.liquidity.sla.nonPerformanceBondPenaltyMax": "0.5",
      "market.liquidity.sla.nonPerformanceBondPenaltySlope": "2",
      "market.liquidity.stakeToCcyVolume": "1.0",
      "market.liquidity.targetstake.triggering.ratio": "0.25",
      "market.liquidityProvision.minLpStakeQuantumMultiple": "5000",
      "market.liquidityProvision.shapes.maxSize": "100",
      "market.margin.scalingFactors": "{\"search_level\": 1.1, \"initial_margin\": 1.5, \"collateral_release\": 1.7}",
      "market.monitor.price.defaultParameters": "{\"triggers\": [{\"auction_extension\": 300, \"horizon\": 43200, \"probability\": \"0.9999999\"}] }",
      "market.stake.target.scalingFactor": "0.0001",
      "market.stake.target.timeWindow": "1h",
      "market.value.windowLength": "2h0m0s",
      "network.checkpoint.timeElapsedBetweenCheckpoints": "5m",
      "network.floatingPointUpdates.delay": "5m",
      "network.markPriceUpdateMaximumFrequency": "5s",
      "network.transaction.defaultgas": "1",
      "network.transactions.maxgasperblock": "3000000",
      "network.transactions.minBlockCapacity": "32",
      "network.validators.ersatz.multipleOfTendermintValidators": "0",
      "network.validators.ersatz.rewardFactor": "0.85",
      "network.validators.incumbentBonus": "0.05",
      "network.validators.minimumEthereumEventsForNewValidator": "3",
      "network.validators.multisig.numberOfSigners": "13",
      "network.validators.tendermint.number": "13",
      "reward.asset": "VOTE",
      "reward.staking.delegation.competitionLevel": "1.3",
      "reward.staking.delegation.delegatorShare": "0.8",
      "reward.staking.delegation.maxPayoutPerEpoch": "9890000000000000000000",
      "reward.staking.delegation.maxPayoutPerParticipant": "700000000000000000000",
      "reward.staking.delegation.minimumValidatorStake": "3000000000000000000000",
      "reward.staking.delegation.minValidators": "5",
      "reward.staking.delegation.optimalStakeMultiplier": "3.0",
      "reward.staking.delegation.payoutDelay": "0h",
      "reward.staking.delegation.payoutFraction": "1.0",
      "rewards.marketCreationQuantumMultiple": "1",
      "snapshot.interval.length": "300",
      "spam.pow.difficulty": "15",
      "spam.pow.hashFunction": "sha3_24_rounds",
      "spam.pow.increaseDifficulty": "0",
      "spam.pow.numberOfPastBlocks": "100",
      "spam.pow.numberOfTxPerBlock": "1000",
      "spam.protection.delegation.min.tokens": "100000000000000000",
      "spam.protection.max.batchSize": "30",
      "spam.protection.max.delegations": "360",
      "spam.protection.max.proposals": "300",
      "spam.protection.max.votes": "300",
      "spam.protection.maxUserTransfersPerEpoch": "10000",
      "spam.protection.minimumWithdrawalQuantumMultiple": "10",
      "spam.protection.minMultisigUpdates": "100000000000000000000",
      "spam.protection.proposal.min.tokens": "2000000000000000000000",
      "spam.protection.voting.min.tokens": "1000000000000000000",
      "spam.protection.applyReferral.min.funds": "0",
      "transfer.fee.factor": "0.001",
      "transfer.minTransferQuantumMultiple": "100",
      "validator.performance.scaling.factor": "0",
      "validators.delegation.minAmount": "1",
      "validators.epoch.length": "2m",
      "validators.vote.required": "0.67",
      "referralProgram.maxReferralTiers": "10",
      "referralProgram.maxReferralRewardFactor": "1",
      "referralProgram.maxReferralDiscountFactor": "1",
      "referralProgram.maxPartyNotionalVolumeByQuantumPerEpoch": "10000",
      "referralProgram.minStakedVegaTokens": "0",
      "referralProgram.maxReferralRewardProportion": "1"
    },
    "network_limits": {
      "propose_market_enabled": true,
      "propose_asset_enabled": true,
      "bootstrap_block_count": 0
    },
    "checkpoint": {
      "load_hash": ""
    }
  }
}

vegaprotocol / vega