anchor.diff:                                             query.NativeBson, @err,
                                              FlagsToNative(AFlags));
     if nativeFile = nil then
  -    raise EMongoGridfs.Create('File not found');
  +    RaiseFindFileError(@err);
   
     Result := NewMongoGridfsFile(nativeFile);
   end;
  
positive.code:   nativeFile: Pointer;
    err: bson_error_t;
  begin
    nativeFile := mongoc_gridfs_find_one_cnv_by_filename(FNativeGridfs,
                                                         PAnsiChar(AName),
                                                         @err, FlagsToNative(AFlags));
    if nativeFile = nil then
      raise EMongoGridfs.Create(@err);
  
    Result := NewMongoGridfsFile(nativeFile);
  end;
  
negative.code:   err: bson_error_t;
    query: IBson;
  begin
    FillChar(err, SizeOf(bson_error_t), 0);
    if AQuery = nil then
      query := NewBson
    else
  