Toaster component throws errors when Toast is closed if a returnElements is not provided in the calling event

[brentswisher]

Expected behavior
There would be no error if returnElements is provided because it defaults to an empty array

Actual behavior
The following error is emitted:

pharos-toaster.js:71 Uncaught TypeError: returnElements is not iterable
    at PharosComponent._focusOnReturnElements (pharos-toaster.js:71:1)
    at PharosComponent._closeToast (pharos-toaster.js:84:1)
    at pharos-toast.js:101:1
    at debounce.js:10:1

Steps to reproduce the issue

1. Create a toast/toaster by emitting a custom event as detailed in the documentation without including a return element:

const event = new CustomEvent("pharos-toast-open", {
        detail: {
            content: "Some problem has occurred",
            status: "error",
        },
    });
    document.dispatchEvent(event);

2. Trigger toast to show and then close
3. See error in browser console

Screenshots or code
I suspect this section is always overwriting the default, even when it isn't defined in the event.

    const { content, status, id, indefinite, returnElements } = (<CustomEvent>event).detail;
    this.returnElements = returnElements;

Pharos version
12.19.2

Your environment

• OS: macOS Ventura
• Browser: Chrome
• Version: 114.0.5735.248

[daneah]

Context: #503