Socket null handling (#1610)

* return null if in connection failure state

* reconnect on connection failure

* better connection handling

* probably not necessary but just incase

* connection handling updates

* add cancelOnError: true

cw_bitcoin/lib/electrum.dart

@@ -66,6 +66,7 @@ class ElectrumClient {
 
     try {
       await socket?.close();
+      socket = null;
     } catch (_) {}
 
     try {
@@ -90,7 +91,8 @@ class ElectrumClient {
     }
     _setConnectionStatus(ConnectionStatus.connected);
 
-    socket!.listen((Uint8List event) {
+    socket!.listen(
+      (Uint8List event) {
         try {
           final msg = utf8.decode(event.toList());
           final messagesList = msg.split("\n");
@@ -103,7 +105,9 @@ class ElectrumClient {
         } catch (e) {
           print(e.toString());
         }
-    }, onError: (Object error) {
+      },
+      onError: (Object error) {
+        socket = null;
         final errorMsg = error.toString();
         print(errorMsg);
         unterminatedString = '';
@@ -113,10 +117,14 @@ class ElectrumClient {
 
         if (currentHost != null && isErrorForCurrentHost)
           _setConnectionStatus(ConnectionStatus.failed);
-    }, onDone: () {
+      },
+      onDone: () {
+        socket = null;
         unterminatedString = '';
         if (host == socket?.address.host) _setConnectionStatus(ConnectionStatus.disconnected);
-    });
+      },
+      cancelOnError: true,
+    );
 
     keepAlive();
   }

cw_bitcoin/lib/electrum_wallet.dart

@@ -218,10 +218,7 @@ abstract class ElectrumWalletBase
       if (electrumClient.isConnected) {
         syncStatus = SyncedSyncStatus();
       } else {
-        if (electrumClient.uri != null) {
+        syncStatus = NotConnectedSyncStatus();
-          await electrumClient.connectToUri(electrumClient.uri!, useSSL: electrumClient.useSSL);
-          startSync();
-        }
       }
     }
   }
@@ -265,6 +262,7 @@ abstract class ElectrumWalletBase
   Future<Isolate>? _isolate;
 
   void Function(FlutterErrorDetails)? _onError;
+  Timer? _reconnectTimer;
   Timer? _autoSaveTimer;
   static const int _autoSaveInterval = 30;
 
@@ -1980,13 +1978,6 @@ abstract class ElectrumWalletBase
         break;
       case ConnectionStatus.failed:
         syncStatus = LostConnectionSyncStatus();
-        // wait for 5 seconds and then try to reconnect:
-        Future.delayed(Duration(seconds: 5), () {
-          electrumClient.connectToUri(
-            node!.uri,
-            useSSL: node!.useSSL ?? false,
-          );
-        });
         break;
       case ConnectionStatus.connecting:
         syncStatus = ConnectingSyncStatus();
@@ -1996,7 +1987,11 @@ abstract class ElectrumWalletBase
   }
 
   void _syncStatusReaction(SyncStatus syncStatus) async {
-    if (syncStatus is NotConnectedSyncStatus) {
+    if (syncStatus is SyncingSyncStatus) {
+      return;
+    }
+
+    if (syncStatus is NotConnectedSyncStatus || syncStatus is LostConnectionSyncStatus) {
       // Needs to re-subscribe to all scripthashes when reconnected
       _scripthashesUpdateSubject = {};
 
@@ -2004,7 +1999,8 @@ abstract class ElectrumWalletBase
 
       _isTryingToConnect = true;
 
-      Future.delayed(Duration(seconds: 10), () {
+      _reconnectTimer?.cancel();
+      _reconnectTimer = Timer(Duration(seconds: 10), () {
         if (this.syncStatus is! SyncedSyncStatus && this.syncStatus is! SyncedTipSyncStatus) {
           this.electrumClient.connectToUri(
                 node!.uri,