[10.x] Avoid TypeError when using json validation rule when PHP < 8.3 (laravel#49474)

* test: validateJson should return false when value is null

Fails with Laravel Framework 10.38.2 in PHP < 8.3, introduced in laravel#49413

* fix: validateJson should return false when value is null

Return false when $value is null.

Avoid TypeError: json_validate(): Argument #1 ($json) must be of type string, null given, when using symfony/polyfill-php83 in PHP < 8.3.

Avoid deprecation warning: json_validate(): Passing null to parameter #1 ($json) of type string is deprecated, when using PHP 8.3.

---------

Co-authored-by: Rogelio Jacinto <[email protected]>

Author: Xint0

Diff for: src/Illuminate/Validation/Concerns/ValidatesAttributes.php

@@ -1430,11 +1430,11 @@ public function validateMacAddress($attribute, $value)
      */
     public function validateJson($attribute, $value)
     {
-        if (is_array($value)) {
+        if (is_array($value) || is_null($value)) {
             return false;
         }
 
-        if (! is_scalar($value) && ! is_null($value) && ! method_exists($value, '__toString')) {
+        if (! is_scalar($value) && ! method_exists($value, '__toString')) {
             return false;
         }
 

Diff for: tests/Validation/ValidationValidatorTest.php

@@ -19,6 +19,7 @@
 use Illuminate\Support\Arr;
 use Illuminate\Support\Carbon;
 use Illuminate\Support\Exceptions\MathException;
+use Illuminate\Support\Stringable;
 use Illuminate\Translation\ArrayLoader;
 use Illuminate\Translation\Translator;
 use Illuminate\Validation\DatabasePresenceVerifierInterface;
@@ -2817,6 +2818,14 @@ public function testValidateJson()
         $trans = $this->getIlluminateArrayTranslator();
         $v = new Validator($trans, ['foo' => ['array']], ['foo' => 'json']);
         $this->assertFalse($v->passes());
+
+        $trans = $this->getIlluminateArrayTranslator();
+        $v = new Validator($trans, ['foo' => null], ['foo' => 'json']);
+        $this->assertFalse($v->passes());
+
+        $trans = $this->getIlluminateArrayTranslator();
+        $v = new Validator($trans, ['foo' => new Stringable('[]')], ['foo' => 'json']);
+        $this->assertTrue($v->passes());
     }
 
     public function testValidateBoolean()