Handle length() correctly for nested structures

[Boris Zhguchev]

given json:

[
{"verb": "TEST","a":[1,2,3]},
{"verb": "TEST","a":[1,2,3]},
{"verb": "TEST"}, {"verb": "RUN"}
]

given jpath:
$.[?(@.verb == 'TEST')].a.length()

Result: [2]
Expected result: [3,3]