Test

src/main.cpp

@@ -383,7 +383,7 @@ void UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) {
     ProcessBlockAvailability(nodeid);
 
     BlockMap::iterator it = mapBlockIndex.find(hash);
-    if (it != mapBlockIndex.end() && it->second->nChainWork > 0) {
+    if (it != 0 && it != mapBlockIndex.end() && it->second->nChainWork > 0) {
         // An actually better block was announced.
         if (state->pindexBestKnownBlock == NULL || it->second->nChainWork >= state->pindexBestKnownBlock->nChainWork)
             state->pindexBestKnownBlock = it->second;