New error when accessing properties of top "Object is possibly 'null'." after upgrading to TS 4.4.3

I recently upgraded my project to TypeScript 4.4.3 from 3.9.9.

My project's using "strictNullChecks": true, in its tsconfig.json, and runs in the browser, not server-side on Node.

In TypeScript 4.4.3, it seems like the type declarations for top has changed to WindowProxy | null (node_modules/typescript/lib/lib.dom.d.ts)

This means that I get the following error¹ wherever I try to access properties of top²: TS Playground

const topUrl = top.window.location.href; // => Object is possibly 'null'.

How can I ignore this category of errors only for when top is possibly null?³

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_{¹ I understand that this error is warning me against the scenario where my website is loaded in an iframe, and therefore can't access top due to XSS. This isn't an issue because my 'X-Frame-Options' is set to 'sameorigin' and will therefore refuse to load my website in a cross-origin iframe.}

_{² I access properties of top because I use iframes inside my project a lot, where it loads sub-pages on the same domain.}

_{³ I could use the following fixes to get around this Object is possibly 'null'., but I'd prefer not to, as my project is quite large and this fix would be tedious with minimal improvement.}

let topUrl = top?.window.location.href || '';

let topUrl = '';
if (top) {
    topUrl = top.window.location.href;
}

_{I could also ignore these errors on every line with // @ts-ignore, but there's a lot of references to top and I don't want to clutter the project (also, other TypeScript errors on the same line would be ignored).}

// @ts-ignore
const topUrl = top.window.location.href;

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