fix: if_exist does not work with array data

Author: kenjis

system/Validation/FormatRules.php

@@ -29,6 +29,10 @@ class FormatRules
      */
     public function alpha($str = null): bool
     {
+        if (is_array($str)) {
+            return false;
+        }
+
         if (! is_string($str)) {
             $str = (string) $str;
         }

system/Validation/Validation.php

@@ -399,8 +399,10 @@ private function processIfExist(string $field, array $rules, array $data)
                         break;
                     }
                 }
-            } else {
+            } elseif (str_contains($field, '.')) {
                 $dataIsExisting = array_key_exists($ifExistField, $flattenedData);
+            } else {
+                $dataIsExisting = array_key_exists($ifExistField, $data);
             }
 
             if (! $dataIsExisting) {