core: update blockProcFeed in insertChain

core/blockchain.go

@@ -1577,8 +1577,6 @@ func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 	if len(chain) == 0 {
 		return 0, nil
 	}
-	bc.blockProcFeed.Send(true)
-	defer bc.blockProcFeed.Send(false)
 
 	// Do a sanity check that the provided chain is actually ordered and linked.
 	for i := 1; i < len(chain); i++ {
@@ -1618,6 +1616,9 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool, makeWitness
 	if bc.insertStopped() {
 		return nil, 0, nil
 	}
+	bc.blockProcFeed.Send(true)
+	defer bc.blockProcFeed.Send(false)
+
 	// Start a parallel signature recovery (signer will fluke on fork transition, minimal perf loss)
 	SenderCacher().RecoverFromBlocks(types.MakeSigner(bc.chainConfig, chain[0].Number(), chain[0].Time()), chain)