lnwallet: fix error propagation for funding messages

Previously, if an error was returned during handleSingleFunderSigs or
handleFundingCounterPartySigs, the wallet would hang waiting for
the completeChan channel to be populated. This commit adds nil returns for
the completeChan when errors are propagated.

lnwallet/wallet.go

@@ -981,7 +981,9 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 			prevOut := txin.PreviousOutPoint
 			output, err := l.ChainIO.GetUtxo(&prevOut.Hash, prevOut.Index)
 			if output == nil {
-				msg.err <- fmt.Errorf("input to funding tx does not exist: %v", err)
+				msg.err <- fmt.Errorf("input to funding tx "+
+					"does not exist: %v", err)
+				msg.completeChan <- nil
 				return
 			}
 
@@ -990,12 +992,17 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 				fundingTx, i, txscript.StandardVerifyFlags, nil,
 				fundingHashCache, output.Value)
 			if err != nil {
-				// TODO(roasbeef): cancel at this stage if invalid sigs?
-				msg.err <- fmt.Errorf("cannot create script engine: %s", err)
+				// TODO(roasbeef): cancel at this stage if
+				// invalid sigs?
+				msg.err <- fmt.Errorf("cannot create script "+
+					"engine: %s", err)
+				msg.completeChan <- nil
 				return
 			}
 			if err = vm.Execute(); err != nil {
-				msg.err <- fmt.Errorf("cannot validate transaction: %s", err)
+				msg.err <- fmt.Errorf("cannot validate "+
+					"transaction: %s", err)
+				msg.completeChan <- nil
 				return
 			}
 
@@ -1022,7 +1029,9 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 	sigHash, err := txscript.CalcWitnessSigHash(witnessScript, hashCache,
 		txscript.SigHashAll, commitTx, 0, channelValue)
 	if err != nil {
-		msg.err <- fmt.Errorf("counterparty's commitment signature is invalid: %v", err)
+		msg.err <- fmt.Errorf("counterparty's commitment signature is "+
+			"invalid: %v", err)
+		msg.completeChan <- nil
 		return
 	}
 
@@ -1034,6 +1043,7 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 		return
 	} else if !sig.Verify(sigHash, theirKey) {
 		msg.err <- fmt.Errorf("counterparty's commitment signature is invalid")
+		msg.completeChan <- nil
 		return
 	}
 	res.partialState.OurCommitSig = theirCommitSig
@@ -1049,6 +1059,7 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 	// Broacast the finalized funding transaction to the network.
 	if err := l.PublishTransaction(fundingTx); err != nil {
 		msg.err <- err
+		msg.completeChan <- nil
 		return
 	}
 
@@ -1058,6 +1069,7 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
 	nodeAddr := res.nodeAddr
 	if err := res.partialState.SyncPending(nodeAddr); err != nil {
 		msg.err <- err
+		msg.completeChan <- nil
 		return
 	}
 
@@ -1076,6 +1088,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	l.limboMtx.RUnlock()
 	if !ok {
 		req.err <- fmt.Errorf("attempted to update non-existant funding state")
+		req.completeChan <- nil
 		return
 	}
 
@@ -1102,6 +1115,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 		pendingReservation.partialState.OurDustLimit)
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}
 	theirCommitTx, err := CreateCommitTx(fundingTxIn, theirCommitKey, ourCommitKey,
@@ -1109,6 +1123,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 		theirBalance, ourBalance, pendingReservation.partialState.TheirDustLimit)
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}
 
@@ -1118,6 +1133,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	err = initStateHints(ourCommitTx, theirCommitTx, req.obsfucator)
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}
 
@@ -1138,6 +1154,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 		txscript.SigHashAll, ourCommitTx, 0, channelValue)
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}
 
@@ -1146,9 +1163,11 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	sig, err := btcec.ParseSignature(req.theirCommitmentSig, btcec.S256())
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	} else if !sig.Verify(sigHash, theirKey) {
 		req.err <- fmt.Errorf("counterparty's commitment signature is invalid")
+		req.completeChan <- nil
 		return
 	}
 	pendingReservation.partialState.OurCommitSig = req.theirCommitmentSig
@@ -1159,6 +1178,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	p2wsh, err := witnessScriptHash(witnessScript)
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}
 	signDesc := SignDescriptor{
@@ -1175,6 +1195,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	sigTheirCommit, err := l.Signer.SignOutputRaw(theirCommitTx, &signDesc)
 	if err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}
 	pendingReservation.ourCommitmentSig = sigTheirCommit
@@ -1183,6 +1204,7 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
 	// which will be used for the lifetime of this channel.
 	if err := pendingReservation.partialState.SyncPending(pendingReservation.nodeAddr); err != nil {
 		req.err <- err
+		req.completeChan <- nil
 		return
 	}