<?php if (isset($a[$xPrefix.'previous'], $a[$trace]) && $a[$xPrefix.'previous'] instanceof \Exception) {
$b = (array) $a[$xPrefix.'previous'];
$class = get_debug_type($a[$xPrefix.'previous']);
self::traceUnshift($b[$xPrefix.'trace'], $class, $b[$prefix.'file'], $b[$prefix.'line']);
$a[$trace] = new TraceStub($b[$xPrefix.'trace'], false, 0, -\count($a[$trace]->value));
}