PHP PDO not inserting or throwing error - php

Question

The email is not being inserted into the database, however I am receiving an echo of success without any errors. I'm not sure what is going wrong. I've tried it with a duplicate email and I get the duplicate email message so it is connecting to the database, and it will not insert when it is a duplicate; however, it seems to not be inserting anything when it is not a duplicate. It seems to just skip the step of uploading.
<?php
include 'db_functions.php';
$_POST['email'] = 'somenewemail#gmail.com';
if(isset($_POST['email']) && ($_POST['email'] != NULL || $_POST['email'] != '')){
$ERRORS = array();
$cleanEmail = htmlentities($_POST['email']);
$database = dbconnlocal();
$queryEmailExists = $database->prepare("SELECT email FROM email_list WHERE email= ?");
$queryUploadEmail = $database->prepare("INSERT INTO email_list (email) VALUES ( ? )");
$database->beginTransaction();
try
{
$queryEmailExists->execute(array($cleanEmail));
$results = $queryEmailExists->fetchAll(PDO::FETCH_ASSOC);
$dbEmail = $results[0]['email'];
if(trim($dbEmail) == trim($cleanEmail)) {
// duplicate email
throw new Exception('duplicateEmail');
} else {
// new email
$queryUploadEmail->execute(array($cleanEmail));
echo json_encode('success');
}
}
catch (Exception $e)
{
switch(trim($e->getMessage())) {
case 'duplicateEmail':
// handle duplicate error
$ERRORS['error'] = 'duplicateEmail';
break;
default:
// handle default errors
$ERRORS['error'] = 'default';
break;
}
echo json_encode($ERRORS['error']);
}
} else { echo json_encode('emptyEmail'); /* empty email */ };
?>