Cannot read properties of undefined (reading 'dateTime')

[FabienPochez]

Hey Milan,
Trying to use your plugin on a website and have this error in the console :
format-google-calendarmin.js:1 Uncaught TypeError: Cannot read properties of undefined (reading 'dateTime')

I suck in js. You think you could help to understand the issue?
website: https://diaradio2.squarespace.com/
pass : mcforever

Thanks!
Fab