Hi Everyone,

   Here i wrote a trigger on task where new task record is inserted or updated ,in account i have custom field called Area__c
   Whenever trigger fires the Area__c filed should outopopulate on task.
   I need your help on without selecting Relatedto(whatid) i am try to save a record it will cause an Attempt to de-reference a null error  how to resove
   this what kind of changes i need to do in trigger.   
   
     Thanks in advance.

trigger Update_Area on Task (before insert, before update)
{    
    set<id> Accids= new set<id>();
    map<id, Account> mapleads = new map<id, Account>();
    Map<Id, List<Task>> whatIds = new Map<Id, List<Task>>{};
    
        for(Task t : trigger.new)
        {
            String objName = t.WhatId.getSObjectType().getDescribe().getName();
            if(t.WhatId!=null )
            {
                if(objName=='Account')
                {
                    Accids.add(t.WhatId);
                }  
            }
        }
    
    list<Account> ldlist = [select id, name,Area__c
                            from Account where id in :Accids];
    
    if(!ldlist.isEmpty())
    {
        for(Account l : ldlist)
        {
            mapleads.put(l.Id, l);
        }
    }        
    for(Task tt: trigger.new)
    {        
        String objName = tt.WhatId.getSObjectType().getDescribe().getName();
        if(tt.WhatId!=null)
        {
            if(objName == 'Account')
            {
                tt.Area__c= mapleads.get(tt.WhatId).Area__c;  
            }
        }  
    }
}