leftJoin followed by select everything has unexpected dropped columns

[Peter Beshai]

Example:

tidy(
  [{ a: 123, b: 345 }, { a: 452, b: 999}],
  leftJoin([{ a: 452, c: 456 }], { by: 'a' }),
  select(T.everything())
)
// output:
[{"a":123,"b":345},{"a":452,"b":999}]

// expected output: 
[{"a":123,"b":345,"c":undefined},{"a":452,"b":999,"c":456}]