fix dart analyzer error

Author: lohanidamodar

templates/dart/lib/package.dart.twig

@@ -2,15 +2,13 @@ library {{ language.params.packageName }};
 
 import 'dart:async';
 import 'dart:typed_data';
+
 import 'src/enums.dart';
-import 'src/client.dart';
 import 'src/service.dart';
 import 'src/input_file.dart';
 import 'src/upload_progress.dart';
 import 'models.dart' as models;
-
 export 'src/response.dart';
-export 'src/client.dart';
 export 'src/exception.dart';
 export 'src/input_file.dart';
 export 'src/upload_progress.dart';

templates/dart/lib/src/client_browser.dart.twig

@@ -119,7 +119,7 @@ class ClientBrowser extends ClientBase with ClientMixin {
     }
 
     while (offset < size) {
-      var chunk;
+      List<int> chunk;
       final end = min(offset + CHUNK_SIZE, size);
       chunk = file.bytes!.getRange(offset, end).toList();
       params[paramName] =