I am Stuck in trailhead module 4 of Apex Basics and Database. Please help me out.
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There was an unexpected error in your org which is preventing this assessment check from completing: System.NullPointerException: Attempt to de-reference a null object

Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.NullPointerException: Attempt to de-reference a null object

my code is :

public class AccountHandler {

    public static Account insertNewAccount (String accName){
        
        
    if(accName!=''){    
        try{
            Account a = new Account(Name=accName);
            insert a;
            System.debug(' Account created');
            return a;
        } catch(Exception e){
            System.Debug('Account not created');
            return null;
        }
    } else {
        return null;
    }
     
        
    }    
}