$regex not working as expected with arrays

[saadtazi]

When trying to find() a property that is nested in an array of arrays, the record is not returned if the child array has more than one element and one or more of those elements match.

Repro steps:

// no regex - returns expected list: 1 element - ok
mingo.find([{l1: [{ tags: ['tag1', 'tag2'] }, {'notags': 'yep'}]}], {'l1.tags': 'tag1'}).all()

// with regex - but searched property is not an array: ok
mingo.find([{l1: [{ tags: 'tag1'}, {'notags': 'yep'}]}], {'l1.tags': {$regex: '.*tag.*', $options: 'i'}}).all()

// with regex - but searched property is an array, with all elements matching: not ok - expected 1, returned 0
mingo.find([{l1: [{ tags: ['tag1', 'tag2'] }, {'tags': ['tag66']}]}], {'l1.tags': {$regex: 'tag', $options: 'i'}}).all();

// with regex - but searched property is an array, only one element matching: not ok - returns 0 elements - expected 1
mingo.find([{l1: [{ tags: ['tag1', 'tag2'] }, {'notags': 'yep'}]}], {'l1.tags': {$regex: 'tag', $options: 'i'}}).all();

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