SFTP: if /path/to/file is a file then /path/to/file/whatever errors

phpseclib/Net/SFTP.php

@@ -1257,6 +1257,9 @@ class Net_SFTP extends Net_SSH2
         $temp = &$this->stat_cache;
         $max = count($dirs) - 1;
         foreach ($dirs as $i => $dir) {
+            if (!is_array($temp)) {
+                return false;
+            }
             if ($i === $max) {
                 unset($temp[$dir]);
                 return true;
@@ -1283,6 +1286,9 @@ class Net_SFTP extends Net_SSH2
 
         $temp = &$this->stat_cache;
         foreach ($dirs as $dir) {
+            if (!is_array($temp)) {
+                return null;
+            }
             if (!isset($temp[$dir])) {
                 return null;
             }