log: Print error message when coindb is in inconsistent state

Author: fjahr

src/txdb.cpp

@@ -123,6 +123,9 @@ bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock, boo
         // We may be in the middle of replaying.
         std::vector<uint256> old_heads = GetHeadBlocks();
         if (old_heads.size() == 2) {
+            if (old_heads[0] != hashBlock) {
+                LogPrintLevel(BCLog::COINDB, BCLog::Level::Error, "The coins database detected an inconsistent state, likely due to a previous crash or shutdown. You will need to restart bitcoind with the -reindex-chainstate or -reindex configuration option.\n");
+            }
             assert(old_heads[0] == hashBlock);
             old_tip = old_heads[1];
         }