Incorrect result when accessing array index

[Stadly]

Data:

{
  "idx": 0,
  "nestedArray": [
    [
      false,
      false
    ]
  ]
}

Expression: nestedArray[$$.idx][0]

JSONata Exerciser: https://try.jsonata.org/loN4IGN1u

I would have expected the result to be false. It is [false, false].

Using version 1.4.1 yields the expected result.

Changing $$.idx to 0 in the expression yields the expected result.

[markmelville]

I can't explain why, but clearly having the "[]" operator followed immediately by another "[]" operator isn't producing the AST that we expect. I found that wrapping the first set in parentheses allows it to work as desired: (nestedArray[$$.idx])[0]