*[<Null safety>](https://dart.dev/null-safety)*
VmoFile.readOnly(Vmo _vmo, VmoSharingMode _sharingMode)
VmoFile.readOnly(this._vmo, this._sharingMode) : assert(_vmo != null), super.readOnly(() { int size = _vmo.getSize().size; return _vmo.read(size).bytesAsUint8List(); }) { if (_vmo == null) { throw Exception('Vmo cannot be null'); } }