adding a sheet produces a javascript error

Steps to Reproduce

1. run keikai with ZK 9.5.0
2. click "New Book" button on the toolbar
3. click "add sheet" button to add a new sheet (left-bottom corner, a plus icon)

Current Result

Uncaught (in promise) TypeError: Cannot read property 'inAccordionMold' of null
at init._sel (zul.tab.wpd:1152)
at init._setSel (zul.tab.wpd:455)
at init.setSelectedTab (zul.tab.wpd:249)
at init.setSheetTabs (zss.wpd:36523)
at init.sheetTabs (zss.wpd:13045)
at init.setSheetTabs (zk.wpd:11140)
at Function._set2 (zk.wpd:12115)
at init.setter.func (zk.wpd:21695)
at init.zk.Widget.zk.$extends.set (zk.wpd:21723)
at setAttr (zk.wpd:30260)

Expected Result

no error, 1 sheet is added