fix(grpc): show error on connect to locked wallet

When connecting to a remote wallet we assume that the wallet is already
unlocked. In the case where it is not already unlocked, forward the
error message to the UI.

Fix #738

app/lib/lnd/lightning.js

@@ -11,6 +11,7 @@ import { mainLog } from '../utils/log'
 import subscribeToTransactions from './subscribe/transactions'
 import subscribeToInvoices from './subscribe/invoices'
 import subscribeToChannelGraph from './subscribe/channelgraph'
+import { getInfo } from './methods/networkController'
 
 // Type definition for subscriptions property.
 type LightningSubscriptionsType = {
@@ -65,7 +66,8 @@ class Lightning {
     const { rpcProtoPath, host, cert, macaroon } = this.lndConfig
 
     // Verify that the host is valid before creating a gRPC client that is connected to it.
-    return await validateHost(host).then(async () => {
+    return validateHost(host)
+      .then(async () => {
         // Load the gRPC proto file.
         // The following options object closely approximates the existing behavior of grpc.load.
         // See https://github.com/grpc/grpc-node/blob/master/packages/grpc-protobufjs/README.md
@@ -93,15 +95,19 @@ class Lightning {
 
         // Wait for the gRPC connection to be established.
         return new Promise((resolve, reject) => {
-        this.service.waitForReady(getDeadline(2), err => {
+          this.service.waitForReady(getDeadline(5), err => {
             if (err) {
-            this.service.close()
               return reject(err)
             }
             return resolve()
           })
         })
       })
+      .then(() => getInfo(this.service))
+      .catch(err => {
+        this.service.close()
+        throw err
+      })
   }
 
   /**

app/lib/lnd/walletUnlocker.js

@@ -74,7 +74,7 @@ class WalletUnlocker {
 
       // Wait for the gRPC connection to be established.
       return new Promise((resolve, reject) => {
-        this.service.waitForReady(getDeadline(2), err => {
+        this.service.waitForReady(getDeadline(5), err => {
           if (err) {
             this.service.close()
             return reject(err)

app/lib/zap/controller.js

@@ -193,6 +193,16 @@ class ZapController {
         else if (e.code === 'LND_GRPC_MACAROON_ERROR') {
           errors.macaroon = e.message
         }
+
+        // The `startLightningWallet` call attempts to call the `getInfo` method on the Lightning service in order to
+        // verify that it is accessible. If it is not, an error 12 is throw whcih is the gRPC code for `UNIMPLEMENTED`
+        // which indicates that the requested operation is not implemented or not supported/enabled in the service.
+        // See https://github.com/grpc/grpc-node/blob/master/packages/grpc-native-core/src/constants.js#L129
+        if (e.code === 12) {
+          errors.host =
+            'Unable to connect to host. Please ensure wallet is unlocked before connecting.'
+        }
+
         // Other error codes such as UNAVAILABLE most likely indicate that there is a problem with the host.
         else {
           errors.host = `Unable to connect to host: ${e.details || e.message}`