chore: migrate to flutter 3.27

lib/data/model/pkg/manager.dart

@@ -22,8 +22,6 @@ enum PkgManager {
         return 'opkg list-upgradable';
       case PkgManager.apk:
         return 'apk list --upgradable';
-      default:
-        return null;
     }
   }
 
@@ -56,8 +54,6 @@ enum PkgManager {
         return 'opkg upgrade $args';
       case PkgManager.apk:
         return 'apk upgrade';
-      default:
-        return null;
     }
   }
 

lib/data/model/server/disk.dart

@@ -104,7 +104,9 @@ class DiskIO extends TimeSeq<List<DiskIOPiece>> {
           !item.dev.startsWith('vd') &&
           !item.dev.startsWith('hd') &&
           !item.dev.startsWith('mmcblk') &&
-          !item.dev.startsWith('sr')) continue;
+          !item.dev.startsWith('sr')) {
+        continue;
+      }
       final (read_, write_) = _getSpeed(item.dev);
       read += read_ ?? 0;
       write += write_ ?? 0;

lib/data/model/sftp/worker.dart

@@ -60,8 +60,6 @@ Future<void> isolateMessageHandler(
         case SftpReqType.upload:
           await _upload(data, mainSendPort, sendError);
           break;
-        default:
-          sendError(Exception('unknown type'));
       }
       break;
     default: