opt.: upgrade linter & fix lint issues

lib/data/model/sftp/req.dart

@@ -75,29 +75,30 @@ class SftpReqStatus {
   }
 
   void onNotify(dynamic event) {
-    switch (event.runtimeType) {
-      case SftpWorkerStatus:
-        status = event;
+    var shouldDispose = false;
+    switch (event) {
+      case SftpWorkerStatus val:
+        status = val;
         if (status == SftpWorkerStatus.finished) {
           dispose();
         }
         break;
-      case double:
-        progress = event;
+      case double val:
+        progress = val;
         break;
-      case int:
-        size = event;
+      case int val:
+        size = val;
         break;
-      case Duration:
-        spentTime = event;
+      case Duration d:
+        spentTime = d;
         break;
       default:
         error = Exception('sftp worker event: $event');
         Loggers.app.warning(error);
-        dispose();
-        break;
+        shouldDispose = true;
     }
     notifyListeners();
+    if (shouldDispose) dispose();
   }
 }
 

lib/data/model/sftp/worker.dart

@@ -55,9 +55,9 @@ Future<void> isolateMessageHandler(
   SendPort mainSendPort,
   SendErrorFunction sendError,
 ) async {
-  switch (data.runtimeType) {
-    case SftpReq:
-      switch (data.type) {
+  switch (data) {
+    case SftpReq val:
+      switch (val.type) {
         case SftpReqType.download:
           await _download(data, mainSendPort, sendError);
           break;