SampleBadMethods.cls

public with sharing class SampleBadMethods {
    
    public class SampleCustomException extends Exception{}


    //This method throws a custom exception, because we have a specific data requirement (positive integers)
    //Without the custom check and exception, this code would run, but not meet our specs
    public static Integer iAddUpPositiveIntegers (Integer intA, Integer intB) {

        //First validate that we have positive integers only
        if (intA <0 || intB <0) {
            throw new SampleCustomException('I only take positive integers!');
        } else {
            return intA + intB;
        }

    }

    //This method will throw a built-in exception because it is attempting to access a value that doesn't exist
    public static void thisIsNotGoingToGoWell() {
        
        List < Account > aList = [SELECT ID, Name FROM Account WHERE Name='Acme'];

        //however many accounts we have with the name "Acme" there sure aren't 51 of them, hence, this will throw an exception
        Account notHere = aList[50];

    }


}