google-meet-grid-view-extension: 2020.4.7 Stopped working some time today, git missing everything since 2020.04.1

I think something must have changed on the google meet site, as this extension was working earlier today, but now it’s not working at all – it doesn’t add its button to the meet UI, and clicking the grid toggle in the extension itself doesn’t do anything any more.

There’s an error in my dev console that I think is coming from this extension:

Error in event handler: TypeError: Cannot read property 'click' of undefined
    at chrome-extension://bjkegbgpfgpikgkfidhcihhiflbjgfic/js/inject.js:41:64

Which corresponds to … code I can’t find in this repo?

// ...
injectScript(chrome.runtime.getURL('js/google-meet-grid-view/grid.user.js'));

//injectScript(chrome.runtime.getURL('js/messaging.js'));
chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
        
        let gridOn = !!document.getElementsByClassName('__gmgv-vid-container').length
        let showOnlyVideo = JSON.parse(localStorage.getItem('gmgv-show-only-video'))
        let highlightSpeaker = JSON.parse(localStorage.getItem('gmgv-highlight-speaker'))
        let includeOwnVideo = JSON.parse(localStorage.getItem('gmgv-include-own-video'))
        console.log(localStorage)

        if(request.hasOwnProperty('startup')){
            console.log('init')
        } else if(request.hasOwnProperty('toggleGrid')){
            document.getElementsByClassName('__gmgv-button')[0].click()
            // ^^^ this line ^^^
// ...

I have version 2020.4.7 installed currently.