Reorder array checks
Reorder array checks

Make sure that `if (isset($arr['__phpseclib_marker']))` is done on an array only.

paragonie-scott/phpseclib,danog/phpseclib,phpseclib/phpseclib,metaclassing/phpseclib,paragonie-scott/phpseclib,danog/phpseclib,terrafrost/phpseclib,metaclassing/phpseclib