docs: use @phpstan-ignore-next-line instead of phpstan-baseline

Author: kenjis

phpstan-baseline.neon.dist

@@ -635,11 +635,6 @@ parameters:
 			count: 1
 			path: system/Throttle/Throttler.php
 
-		-
-			message: "#^Variable \\$error on left side of \\?\\? always exists and is always null\\.$#"
-			count: 1
-			path: system/Validation/Validation.php
-
 		-
 			message: "#^Property CodeIgniter\\\\View\\\\Cell\\:\\:\\$cache \\(CodeIgniter\\\\Cache\\\\CacheInterface\\) in empty\\(\\) is not falsy\\.$#"
 			count: 2

system/Validation/Validation.php

@@ -331,6 +331,7 @@ protected function processRules(
 
                 $param = ($param === false) ? '' : $param;
 
+                // @phpstan-ignore-next-line $error may be set by rule methods.
                 $this->errors[$field] = $error ?? $this->getErrorMessage(
                     $rule,
                     $field,