From f0b92fc3cd83c7f9d5aff3007460d1343f1b3d31 Mon Sep 17 00:00:00 2001
From: kenjis <kenji.uui@gmail.com>
Date: Wed, 22 Nov 2023 10:31:22 +0900
Subject: [PATCH 1/2] refactor: fix type error

$param is ?string.
---
 system/Validation/Validation.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/system/Validation/Validation.php b/system/Validation/Validation.php
index 853ba080402d..100e36c7bece 100644
--- a/system/Validation/Validation.php
+++ b/system/Validation/Validation.php
@@ -327,6 +327,7 @@ protected function processRules(
                     $found = true;
 
                     if ($rule === 'field_exists') {
+                        $param  = ($param === false) ? null : $param;
                         $passed = $set->{$rule}($value, $param, $data, $error, $originalField);
                     } else {
                         $passed = ($param === false)

From 5f1d0a5a75af4009c66039a08892886758898866 Mon Sep 17 00:00:00 2001
From: kenjis <kenji.uui@gmail.com>
Date: Wed, 22 Nov 2023 10:39:22 +0900
Subject: [PATCH 2/2] refactor: change $param value

---
 system/Validation/Validation.php | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/system/Validation/Validation.php b/system/Validation/Validation.php
index 100e36c7bece..ec835c5212fd 100644
--- a/system/Validation/Validation.php
+++ b/system/Validation/Validation.php
@@ -300,7 +300,8 @@ protected function processRules(
             $arrayCallable  = $isCallable && is_array($rule);
 
             $passed = false;
-            $param  = false;
+            /** @var string|null $param */
+            $param = null;
 
             if (! $isCallable && preg_match('/(.*?)\[(.*)\]/', $rule, $match)) {
                 $rule  = $match[1];
@@ -327,10 +328,9 @@ protected function processRules(
                     $found = true;
 
                     if ($rule === 'field_exists') {
-                        $param  = ($param === false) ? null : $param;
                         $passed = $set->{$rule}($value, $param, $data, $error, $originalField);
                     } else {
-                        $passed = ($param === false)
+                        $passed = ($param === null)
                             ? $set->{$rule}($value, $error)
                             : $set->{$rule}($value, $param, $data, $error, $field);
                     }
@@ -356,8 +356,6 @@ protected function processRules(
                     $value = json_encode($value);
                 }
 
-                $param = ($param === false) ? '' : $param;
-
                 $fieldForErrors = ($rule === 'field_exists') ? $originalField : $field;
 
                 // @phpstan-ignore-next-line $error may be set by rule methods.