Fix soft crash with Element call widgets (#10684)

There was a race condition somewhere which would cause a soft crash
of the whole app because WidgetPip here gets the currently active
widget given a widget ID and room, but this can race and be null.

Co-authored-by: Janne Mareike Koschinski <janne@kuschku.de>

src/components/views/pips/WidgetPip.tsx

@@ -123,7 +123,7 @@ export const WidgetPip: FC<Props> = ({ widgetId, room, viewingRoom, onStartMovin
                 pointerEvents="none"
                 movePersistedElement={movePersistedElement}
             />
-            {(call !== null || WidgetType.JITSI.matches(widget.type)) && (
+            {(call !== null || WidgetType.JITSI.matches(widget?.type)) && (
                 <Toolbar className="mx_WidgetPip_footer">
                     <RovingAccessibleTooltipButton
                         onClick={onLeaveClick}