I saw something simillar here: Qlik sense 3.2.3 issue · Issue #17 · erikwett/qsVariable · GitHub
Check the declaration of app - it should be without any reference in currApp method:
var myApp = qlik.currApp();
Hope this helps.
Some of our API's went broken in Qlik Sense 3.2.3, the extention app model have been accidentally moved.
If you are not using your extension in a multi apps mashup, a viable workaroud will be to remove "this" from qlik.currApp(this) it will fallback on the current open app.
I hope this helps