Hi Goutham,
Greetings from Syncfusion support.
We have validated your query “When I resize the window using the browser console getting console error as "Cannot read property 'querySelector' of null”.
We have already considered this as a bug and resolved the issue in package version 18.4.48.
Can you please upgrade your package to this version and ensure the issue on your end?
Regards,
Revanth