Use JSON library to handle marshalling consistent with REST APIs

src/main/php/com/openai/tools/Calls.class.php

@@ -3,6 +3,7 @@
 use Throwable as Any;
 use lang\reflection\TargetException;
 use lang\{Type, Throwable, IllegalArgumentException};
+use text\json\Json;
 use util\data\Marshalling;
 
 /**
@@ -109,9 +110,8 @@ public function call($name, $arguments, $context= []) {
     try {
       list($instance, $method)= $this->functions->target($name);
 
-      $named= json_decode($arguments, null, 512, JSON_OBJECT_AS_ARRAY | JSON_THROW_ON_ERROR);
       $pass= [];
-      foreach ($this->pass($method, $named, $context) as $type => $value) {
+      foreach ($this->pass($method, Json::read($arguments), $context) as $type => $value) {
         $pass[]= $this->marshalling->unmarshal($value, $type);
       }
 
@@ -122,6 +122,6 @@ public function call($name, $arguments, $context= []) {
       $result= $this->error(Throwable::wrap($e));
     }
 
-    return json_encode($result);
+    return Json::of($result);
   }
 }

src/test/php/com/openai/unittest/CallsTest.class.php

@@ -64,7 +64,7 @@ public function call_successfully() {
   #[Test]
   public function call_invalid_json() {
     Assert::equals(
-      '{"error":"lang.Error","message":"Control character error, possibly incorrectly encoded"}',
+      '{"error":"lang.FormatException","message":"Unclosed string "}',
       (new Calls($this->functions))->call('testing_greet', '{"unclosed')
     );
   }