zss throws a javascript error when quickly switching sheets

Steps to Reproduce

1. load attached file
2. set network throttling to Fast 3G to simulate longer latency
3. select 4th sheet
4. select 5th sheet
5. repeat selecting 2 sheets interchangeably, before one sheet renders completely select another sheet

Current Result

>zk.wpd:20638 Uncaught TypeError: Cannot read property 'text' of undefined
at init.$init (zss.wpd:6513)
at new init (zk.wpd:9850)
at init.$init (zss.wpd:5771)
at new init (zk.wpd:9850)
at init.doSheetSelected (zss.wpd:17487)
at init.sheetId (zss.wpd:575)
at init.setSheetId (zk.wpd:9889)
at Function._set2 (zk.wpd:10333)
at init.setter.func (zk.wpd:15882)
at init.zk.Widget.zk.$extends.set (zk.wpd:15910)

Expected Result

no error

Workaround

select sheets slower