Fix configuration with .screepsrc

[Hiestaa]

I tried without success to configure this module using the .screepsrc method. I believe I am using Node v10, but I am not sure as I am running screeps server on windows through steam.

Digging through code, it appears that this line doesn't work as I would have expected:

Object.assign(opts.history, DEFAULTS, opts.history, ENV)

I would expect the above to pick values from ENV, then opts.history, then DEFAULT. And thus, with an empty ENV and values in opts.history, it should override the default.

However, that's not what happens. Consider this example:

> a = {x: 1, y: 2}
{ x: 1, y: 2 }
> b = {x: 10, y: 20}
{ x: 10, y: 20 }
> Object.assign(a, b, a)
{ x: 10, y: 20 }
> a
{ x: 10, y: 20 }

I believe what happens internally in Object.assign(a, b, a) is something along those lines:

• Set a.x (first param) to b.x (second param), which set a.x to 10
• Set a.x (first param) to a.x (second param) as the last param takes priority, but now a.x = 10 and thus we're just overriding a.x with the same value, a.x.
• Same with a.y and b.y

It does not happen with the following code, because the object being set is brand new:

> a = Object.assign({}, a, b, a)
{ x: 1, y: 2 }
> a
{ x: 1, y: 2 }

I made the update in my local node_modules and the config in ./.screepsrc is honored.

If you're able to reproduce the problem on your end here is a fix for you! I think this might still be good to ship because that's the way MDN recommend to do merging:

Merging objects with same properties

const o1 = { a: 1, b: 1, c: 1 };
const o2 = { b: 2, c: 2 };
const o3 = { c: 3 };

const obj = Object.assign({}, o1, o2, o3);
console.log(obj); // { a: 1, b: 2, c: 3 }

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Merging_objects_with_same_properties