Workaround tabIndex=-1 added to document body by SvelteKit

This ends up producing a lot of extra focus events that normally would not exist.

Fixes #36
Fixes #39

src/lib/components/popover/Popover.svelte

@@ -137,7 +137,11 @@
   onMount(() => registerPopover?.(registerBag));
 
   // Handle focus out
-  function handleFocus() {
+  function handleFocus(event: FocusEvent) {
+    if (event.target === window.document.body) {
+      // Workaround for a SvelteKit issue: https://github.com/sveltejs/kit/issues/3501
+      return;
+    }
     if (popoverState !== PopoverStates.Open) return;
     if (isFocusWithinPopoverGroup()) return;
     if (!button) return;