From 05e8d7f2258a7444696ba70b76d0c1c909046315 Mon Sep 17 00:00:00 2001
From: atvanguard <3612498+atvanguard@users.noreply.github.com>
Date: Thu, 18 Jan 2024 15:55:09 +0000
Subject: [PATCH] handle new trader

---
 plugin/evm/orderbook/memory_database.go | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/plugin/evm/orderbook/memory_database.go b/plugin/evm/orderbook/memory_database.go
index 7eeab0b4b1..bf1aa647b4 100644
--- a/plugin/evm/orderbook/memory_database.go
+++ b/plugin/evm/orderbook/memory_database.go
@@ -1289,10 +1289,21 @@ func (db *InMemoryDatabase) GetOrderValidationFields(orderId common.Hash, order
 		bidsHead = db.LongOrders[marketId][0].Price
 	}
 
+	availableMargin := big.NewInt(0)
+	if db.TraderMap[trader] != nil {
+		// backwards compatibility
+		if db.TraderMap[trader].Margin.Available == nil {
+			db.TraderMap[trader].Margin.Available = big.NewInt(0)
+		}
+		if db.TraderMap[trader].Margin.VirtualReserved == nil {
+			db.TraderMap[trader].Margin.Available = big.NewInt(0)
+		}
+		availableMargin = hu.Sub(db.TraderMap[trader].Margin.Available /* as fresh as the last matching engine run */, db.TraderMap[trader].Margin.VirtualReserved)
+	}
 	return OrderValidationFields{
 		Exists:          false,
 		PosSize:         posSize,
-		AvailableMargin: hu.Sub(db.TraderMap[trader].Margin.Available /* as fresh as the last matching engine run */, db.TraderMap[trader].Margin.VirtualReserved),
+		AvailableMargin: availableMargin,
 		AsksHead:        asksHead,
 		BidsHead:        bidsHead,
 	}