PHP: nested try-catch does not work within a function - php

Question

Recently I have started playing around with Exceptions and their handling. Everything seemed to work just fine however I have just hit a brick wall and I'm not sure if there is a solution for my problem or should I remake my code base.
Situation:
I'm executing a small piece of code inside try block and I'm catching all exceptions and simply logging/outputing the errors. I'm trying to execute a function which deletes object from database:
It removes the relationships;
It removes the object.
What I want to accomplish is: if object removal fails - restore previously removed relationships.
I thought that putting a nested try-catch block inside a function at the place where the final deletion is being performed I would catch an exception and revert the changes, however this does not work inside a function and it simply ignores the try-catch block and goes to the top one.
HOWEVER: When I put the same piece of code outside of the function it works just fine and like intended!
Below are two pieces of code - working and not working.
EDIT: I forgot to mention that I purposely made a syntax mistake in "router" DELETE query and it always throws an exception during "$status_r = \sys\database\query($query, $db, $elem_t, $elem);" execution. In the first case it ignores the try-catch block inside the function "delete" and goes to the top try-catch block where function is called.
NOT WORKING AS INTENDED
try
{
$db = \sys\database\connect();
$status = ips\routers\delete($id, $db);
echo "success";
\sys\core\log_action("router_delete", "success", "Router '$id' successfully deleted", $db);
}
catch (Exception $ex)
{
echo (sys\errors\is_error($ex->getMessage())) ? sys\errors\parse($ex->getMessage()) : $ex->getMessage();
\sys\core\log_action("router_delete", "failure", $ex->getMessage(), $db);
}
Code inside delete function:
function delete($id, &$db = false)
{
// Check if Any Interfaces are set on this router
if (\ips\interfaces\exists(array("router", $id), $db) !== false)
throw new \Exception(\sys\errors\exist("Router has active interfaces and cant be removed!"));
$curr_ip_id = \ips\ips\get(array("router_id", $id), "id", $db);
if (!\sys\validation\validate("numeric", $curr_ip_id[0]['id']))
throw new \Exception(\sys\errors\database());
$status = \ips\ips\revoke($curr_ip_id[0]['id'], NULL, $db);
if ($status === true)
{
// if we get an error we need to revert changes - aka rebind IP to router
try
{
$query = "DELETE FROM routers WHERE i = ?";
$elem_t = "i";
$elem = array($id);
$status_r = \sys\database\query($query, $db, $elem_t, $elem);
if ($status_r === true)
return true;
else
throw new \Exception();
}
catch (Exception $ex)
{
$status_rebind = \ips\ips\set_owner(array("id", $curr_ip_id[0]['id']), $id, "router", $db);
if ($status_rebind === true)
throw \Exception(\sys\errors\database("Failed Deleting router at the last step. IP reassigned successfully!"));
else
throw \Exception(\sys\errors\database("Failed Deleting router at the last step. IP reassigned failed!"));
}
}
else
throw new \Exception(\sys\errors\database("Failed revoking IP address from router!"));
}
WORKING AS INTENDED
try
{
$db = \sys\database\connect();
if (\ips\interfaces\exists(array("router", $id), $db) !== false)
throw new \Exception(\sys\errors\exist("Router has active interfaces and cant be removed!"));
$curr_ip_id = \ips\ips\get(array("router_id", $id), "id", $db);
if (!\sys\validation\validate("numeric", $curr_ip_id[0]['id']))
throw new \Exception(\sys\errors\database());
$status = \ips\ips\revoke($curr_ip_id[0]['id'], NULL, $db);
if ($status === true)
{
// if we get an error we need to revert changes - aka rebind IP to router
try
{
$query = "DELETE FROM routers WHERE i = ?";
$elem_t = "i";
$elem = array($id);
$status_r = \sys\database\query($query, $db, $elem_t, $elem);
if ($status_r === true)
return true;
else
throw new \Exception();
}
catch (Exception $ex)
{
$status_rebind = \ips\ips\set_owner(array("id", $curr_ip_id[0]['id']), $id, "router", $db);
if ($status_rebind === true)
throw new \Exception(\sys\errors\database("Failed Deleting router at the last step. IP reassigned successfully!"));
else
throw new \Exception(\sys\errors\database("Failed Deleting router at the last step. IP reassigned failed!"));
}
}
else
throw new \Exception(\sys\errors\database("Failed revoking IP address from router!"));
}
catch (Exception $ex)
{
echo (sys\errors\is_error($ex->getMessage())) ? sys\errors\parse($ex->getMessage()) : $ex->getMessage();
\sys\core\log_action("router_delete", "failure", $ex->getMessage(), $db);
}
I'm not exactly sure why try-catch does not work inside the function. Any help would be highly appreciated.
Thanks in advance!