fix a bug parse directory with any classes.

Author: smeghead

.gitignore

@@ -2,4 +2,5 @@
 *.phar
 *.un~
 composer.lock
-.vscode
+.vscode
+tmp

src/Php/PhpReader.php

@@ -49,6 +49,7 @@ public static function parseFile(string $directory, string $filename, Options $o
         }
 
         $relativePath = mb_substr($filename, mb_strlen($directory) + 1);
+        $classes = [];
         foreach (self::getClasses($relativePath, $ast) as $class) {
             $classes[] = new self($directory, $filename, $class);
         }