setIn doesn't always create arrays for numeric keys

[adierkens]

I've noticed some discrepancies when using numeric keys w/ setIn

Consider the following:

setIn(undefined, ['x', 0, 'y'], true)
// { x: { '0': { y: true } } }

setIn({}, ['x', 0, 'y'], true)
// { x: [ { y: true } ] }

I would expect both examples to result in the same outcome, but for some reason it decided to use 0 as a key for a new object, rather than an index in an array.

There are other use cases with similar outcomes:

setIn(undefined, [0, 'y', 'z'], true)
// [ { y: { z: true } } ]

setIn(undefined, ['x', 0, 'y', 'z'], true)
// { x: { '0': { y: { z: true} } } }

Again, I would expect the second to produce an array, rather than an object.

[guigrpa]

Thanks for the report and PR! Released in v1.2.4

[adierkens]

Thanks for the quick release!