getChildByName is set as optional in v6

Updating to pixi v6 we’ve run in to a minor issue. The method getChildByName on Container is set as optional. Is this method (and other attributes added via GlobalMixins) actually undefined at any point, or is the typing wrong? We’re using the method frequently in our code base and it’s tedious to add falsy checks everywhere. If it’s actually not guaranteed to be defined, then we will of course do the checks, but I suspect that it’s actually always defined.

Also, I don’t understand why the method is moved to a mixin and not defined on the class directly as it was in v5.

In summary, this boils down to two questions:

1. Is the getChildByName not always guaranteed to be defined and the typing is correct, or not?
2. What’s the reasoning behind the GlobalMixins and why was getChildByName moved there in v6?

Thanks in advance!

// https://github.com/pixijs/pixi.js/blob/dev/packages/mixin-get-child-by-name/global.d.ts
declare namespace GlobalMixins
{
    interface DisplayObject
    {
        name?: string;
    }

    interface Container
    {
        getChildByName?(name: string, isRecursive?: boolean): import('@pixi/display').DisplayObject;
    }
}

[ShukantPal]

Yeah, but since the typings is declared in the mixin package, it shouldn’t be optional.

[bigtimebuddy]

@ivanpopelyshev Each mixin package has own local global.d.ts file. These typings should definitely not be optional. I believe this probably an artifact of the development of the GlobalMixins and moving stuff around. If you’re installing @pixi/mixin-get-child-by-name this is expected behavior.

This should look more like the Application plugins, for instance: https://github.com/pixijs/pixi.js/blob/8c42699aae78199a4cfd1feeef6dc862afd724fe/packages/ticker/global.d.ts#L1-L15

I believe @MrEmanuel is correct here. There are likely other places this occurs too.