Menu toggle on home page broken

[freshstrangemusic]

If your viewport is narrow enough to show the hamburger menu toggle on the home page, clicking it will not expand a menu:

Uncaught TypeError: can't access property "backdrop", this._config is undefined
    _initializeBackDrop https://experimenter.services.mozilla.com/static/nimbus_ui/app.bundle.js:2
    Ur https://experimenter.services.mozilla.com/static/nimbus_ui/app.bundle.js:2
    getOrCreateInstance https://experimenter.services.mozilla.com/static/nimbus_ui/app.bundle.js:2
    5414 https://experimenter.services.mozilla.com/static/nimbus_ui/app.bundle.js:2
    r https://experimenter.services.mozilla.com/static/nimbus_ui/app.bundle.js:2
4 [app.bundle.js:2:514881](https://experimenter.services.mozilla.com/static/nimbus_ui/app.bundle.js)

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