i am facing $A.getCallback() [Cannot read property 'style' of null] Error after upgrading my sandbox to spring 21.

Code block:

//To set the horizontal scroll bar at bottom 
if(totalrec.length < 15){            
   document.getElementById("Table").style.height = totalrec.length+5;
}
else
{
    document.getElementById("Table").style.height = "auto";
}

Above code block is working fine till winter 21 upgrade. Please suggest solution for this.

 

There seems to be an import data missing which is required to complete this superbadge.  Fifth bullet under Prework and Notes says, After installing the unmanaged package, navigate to the Data Import tab on the SolarBots app and select Import.  There isn't any link for importing any file?  I was in midst of doing superbadge for reports and dashboard for classic but it expired yesterday.  So I started with this lightning one now, but stuck.