GraphOptions.joinOperation is incorrectly typed as required

[IlyaSemenov]

GraphOptions.joinOperation is typed as required here:

objection.js/typings/objection/index.d.ts

Lines 752 to 758 in 412bb77

	export interface GraphOptions {
	minimize?: boolean;
	separator?: string;
	aliases?: string[];
	joinOperation: string;
	maxBatchSize?: number;
	}

which is not correct because it defaults to leftJoin.

In particular, this leads to Typescript error in innocent uses like:

MyModel.query().withGraphFetched("foo", { maxBatchSize: 1 })

result:

Argument of type '{ maxBatchSize: number; }' is not assignable to parameter of type 'GraphOptions'.
  Property 'joinOperation' is missing in type '{ maxBatchSize: number; }' but required in type 'GraphOptions'.ts(2345)

[MatiasMinian]

Isn't also aliases incorrectly typed? We are having issues as well having the joinOperation as mandatory, but a bigger problem for us is the aliases which asks for a string[]. Based on the docs, it should be an object right?
Shouldn't it be: aliases?: { [key: string]: string }?

By the way, thanks for this amazing library!

[ibrahimjamil]

poor typescript types