Change path expression array handling rules

[shortercode]

Path expressions use an automatic packing/unpacking algorithm in several places. It works on 2 equivalency rules, where any place one would be accepted the other must also. Also when resolving a value the latter is the preferred output.

[ value ] == value
[] == undefined

This means in some scenarios you will get a value or undefined instead of an array when the input data changes, making the expressions somewhat unpredictable.

I propose we modify this behaviour slightly to make it more predictable. We unfortunately cannot do this everywhere as it breaks some nice to haves.

• path expressions will always resolve to an array.
• field expressions will normally resolve to an array but may also resolve to the value of the only element or undefined.
• wildcard expressions will normally resolve to an array but may also resolve to the value of the only element or undefined.

let output = ({ a: 1 }).a