From 31272f12b34af569ae2f5acd53f4d624d2bee30c Mon Sep 17 00:00:00 2001
From: Bas van Kervel <basvankervel@ziggo.nl>
Date: Tue, 26 May 2015 14:33:11 +0200
Subject: [PATCH] miner crash due to blockchain db close

---
 miner/worker.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/miner/worker.go b/miner/worker.go
index 5e4ff7510f..eb8fe90057 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -288,6 +288,10 @@ func (self *worker) makeCurrent() {
 	current.ownedAccounts = accountAddressesSet(accounts)
 
 	parent := self.chain.GetBlock(current.block.ParentHash())
+	if parent == nil {
+		// in case geth quits the blockchain db can be closed and this returns nil
+		return
+	}
 	current.coinbase.SetGasPool(core.CalcGasLimit(parent))
 
 	self.current = current