WordPress theme not compatible

[Rasel Xs]

Hi,
I'm trying to add fullCalendar in WordPress. but its work only Twenty Twenty One theme. its not working others theme like astra, hello elementor etc.
see the error https://prnt.sc/24u4ece

Please advise me how can I fix this error

Thanks

[Dylan Ferris]

Please refer to the support page and use Stack Overflow for help. If this is a bug, please supply a runnable, stripped-down demonstration.