anchor.diff:          _data = _data.getRange(0, read);
         }
         _position = 0;
  +      _activeFillBufferCall = false;
   
         if (_fileLength == _filePosition) {
           _closeFile();
         }
         _checkScheduleCallbacks();
  +    });
  +    future.handleException((e) {
  +      _activeFillBufferCall = false;
  +      _reportError(e);
  +      return true;
       });
     }
   
  
positive.code:   }
  
    _FileInputStream.fromStdio(int fd)
        : _data = [],
          _position = 0,
          _filePosition = 0 {
      assert(fd == 0);
  
negative.code:   }
  
    void _close() {
      _data = const [];
      _position = 0;
      _filePosition = 0;
      _fileLength = 0;
  