SQLite doesn't fail with empty path

HHVM Version

HipHop VM 3.15.0-dev (rel)
Compiler: heads/master-0-g438b54f98e0f85f0ed59e9921dd4f7ccb83fcab9
Repo schema: cff2737467d2ca6d2896b717c762ddbdbe7b0f72

Standalone code, or other way to reproduce the problem

<?php
$x = new SQLite3('');

Expected result (PHP 7, already formatted as PHPT test)

PHP Fatal error:  Uncaught Exception: Unable to expand filepath in %s:2
Stack trace:
#0 %s(2): SQLite3->__construct('')
#1 {main}
  thrown in %s on line 2

Actual result (HHVM)

No output