Minz request avoid custom methods (#4020)

Take advantage of PHP7+ null-coalescing operator `??` to make code more standard, shorter, and faster instead of custom function with no extra functionality.

Allows code to be better tested and fix two PHPstan errors:

```
 ------ -----------------------------------------
  Line   app/Controllers/configureController.php
 ------ -----------------------------------------
  410    Cannot unset offset 'rid' on string.
 ------ -----------------------------------------

 ------ ------------------------------------
  Line   lib/Minz/FrontController.php
 ------ ------------------------------------
  70     Cannot unset offset 'c' on string.
  71     Cannot unset offset 'a' on string.
 ------ ------------------------------------
```

https://github.com/FreshRSS/FreshRSS/issues/4016

1 files changed, 1 insertions, 1 deletions

diff --git a/app/Models/Auth.php b/app/Models/Auth.php
index 709a80f84..04bd4291f 100644
--- a/app/Models/Auth.php
+++ b/app/Models/Auth.php
@@ -223,7 +223,7 @@ class FreshRSS_Auth {
 	public static function isCsrfOk($token = null) {
 		$csrf = Minz_Session::param('csrf');
 		if ($token === null) {
-			$token = Minz_Request::fetchPOST('_csrf');
+			$token = $_POST['_csrf'] ?? '';
 		}
 		return $token != '' && $token === $csrf;
 	}