Used test code:

$f = fopen(FULL_PATH . '/system/config.php', 'r');
test($f);

function test($file)
{
	throw new RuntimeException('Test');
}

Test Plan

1. Configure debugger to be enabled
2. Modify index php. Add test code after $application->Init();
3. Open some front-end page
4. Confirm that RuntimeException: Test error message is shown in debugger
5. Click on Function link it the backtrace block before error message
6. Confirm, that value of resource type parameter is displayed correctly, like Resource id #n, where n is some integer value