fix(autocomplete): cartesian product mistake

[chizukicn]

When the Cartesian product function is passed in an array of length 1, the return value is mistake.

    const a = ['a', 'b', 'c']
    cartesian([a])
    // we need [['a'],['b'],['c']], not ['a','b','c']

This will cause problems with single-length group autocomplete part when fuzzy matching

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