Added PDOStatement->fetchObject() stub (#4693)

* Added PDOStatement->fetchObject() stub

* fix stub param

* fix Xdebug spelling

* Use extension_loaded check instead

Co-authored-by: Matthew Brown <github@muglug.com>

src/Psalm/Config.php

@@ -1822,6 +1822,16 @@ class Config
             $core_generic_files[] = $stringable_path;
         }
 
+        if (\extension_loaded('PDO')) {
+            $ext_pdo_path = dirname(__DIR__, 2) . '/stubs/pdo.php';
+
+            if (!file_exists($ext_pdo_path)) {
+                throw new \UnexpectedValueException('Cannot locate pdo classes');
+            }
+
+            $core_generic_files[] = $ext_pdo_path;
+        }
+
         if (\extension_loaded('ds')) {
             $ext_ds_path = dirname(__DIR__, 2) . '/stubs/ext-ds.php';
 
@@ -1838,7 +1848,7 @@ class Config
             $xdebug_stub_path = dirname(__DIR__, 2) . '/stubs/Xdebug.php';
 
             if (!file_exists($xdebug_stub_path)) {
-                throw new \UnexpectedValueException('Cannot locate XDebug stub');
+                throw new \UnexpectedValueException('Cannot locate Xdebug stub');
             }
 
             $stub_files[] = $xdebug_stub_path;

stubs/pdo.php

@@ -0,0 +1,10 @@
+<?php
+
+class PdoStatement {
+    /**
+     * @template T
+     * @param class-string<T> $class
+     * @return false|T
+     */
+    public function fetchObject($class = "stdclass") {}
+}