chainntnfs: signal reorg notification before required confirmations

In this commit, we send the reorg notification even when the
transaction has not yet reached the required confirmations, in
case the caller is interested in knowing about it.

Signed-off-by: Nishant Bansal <nishant.bansal.282003@gmail.com>

chainntnfs/txnotifier.go

@@ -2011,6 +2011,20 @@ func (n *TxNotifier) dispatchConfReorg(ntfn *ConfNtfn,
 	if !ntfn.dispatched {
 		confHeight := heightDisconnected + ntfn.NumConfirmations - 1
 		ntfnSet, exists := n.ntfnsByConfirmHeight[confHeight]
+
+		// We also signal the reorg to the notifier in case the
+		// subscriber is also interested in the reorgs before the
+		// transaction received its required confirmation.
+		//
+		// Because as soon as a new block is connected which has the
+		// transaction included again we preemptively read the buffered
+		// channel.
+		select {
+		case ntfn.Event.NegativeConf <- int32(n.reorgDepth):
+		case <-n.quit:
+			return ErrTxNotifierExiting
+		}
+
 		if exists {
 			delete(ntfnSet, ntfn)
 		}