ReferenceError with async function

Question

I'm trying to automate something by running some javascript in the browser console. Basically, what the script is supposed to do is:

1. Click something
2. Wait for a loading animation div to disappear
3. Do something else

I'm having issues with my wait function. I suspect my approach is wrong, but for some reason I get an error just trying to call it. I get this error twice when I run my code:

Uncaught (in promise) ReferenceError: waitForLoad is not defined ReferenceError: waitForLoad is not defined

My code:

button.click() // causes a loading animation div to appear

await waitForLoad();

console.log('Done waiting');

async function waitForLoad() {
    let isWaiting = true;

    while (isWaiting) {
        await sleep(200);
        isWaiting = nodeExists('div.load-animation');
    }

}

function nodeExists(selector) {
    return document.querySelectorAll(selector).length > 0;
}

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}