Don't emit warnings for circular values

src/Exception/NotCallableException.php

@@ -14,7 +14,7 @@ public static function fromInvalidCallable($value, bool $containerEntry = false)
     {
         if (is_object($value)) {
             $message = sprintf('Instance of %s is not a callable', get_class($value));
-        } elseif (is_array($value) && isset($value[0], $value[1])) {
+        } elseif (is_array($value) && array_key_exists(0, $value) && array_key_exists(1, $value)) {
             $class = is_object($value[0]) ? get_class($value[0]) : $value[0];
 
             $extra = method_exists($class, '__call') || method_exists($class, '__callStatic')
@@ -23,9 +23,9 @@ public static function fromInvalidCallable($value, bool $containerEntry = false)
 
             $message = sprintf('%s::%s() is not a callable.%s', $class, $value[1], $extra);
         } elseif ($containerEntry) {
-            $message = var_export($value, true) . ' is neither a callable nor a valid container entry';
+            $message = print_r($value, true) . ' is neither a callable nor a valid container entry';
         } else {
-            $message = var_export($value, true) . ' is not a callable';
+            $message = print_r($value, true) . ' is not a callable';
         }
 
         return new self($message);

tests/Exception/NotCallableExceptionTest.php

@@ -0,0 +1,65 @@
+<?php declare(strict_types=1);
+
+namespace Invoker\Test\Exception;
+
+use Invoker\Exception\NotCallableException;
+use PHPUnit\Framework\TestCase;
+use stdClass;
+
+class NotCallableExceptionTest extends TestCase
+{
+    /**
+     * @test
+     */
+    #[\PHPUnit\Framework\Attributes\Test]
+    public function handles_object_with_circular_reference()
+    {
+        $obj = new stdClass();
+        $obj->self = $obj;
+
+        $exception = NotCallableException::fromInvalidCallable($obj);
+
+        $this->assertSame('Instance of stdClass is not a callable', $exception->getMessage());
+    }
+
+    /**
+     * @test
+     */
+    #[\PHPUnit\Framework\Attributes\Test]
+    public function handles_array_with_object_and_null_method()
+    {
+        $obj = new stdClass();
+
+        $exception = NotCallableException::fromInvalidCallable([$obj, null]);
+
+        $this->assertSame('stdClass::() is not a callable.', $exception->getMessage());
+    }
+
+    /**
+     * @test
+     */
+    #[\PHPUnit\Framework\Attributes\Test]
+    public function handles_circular_array_reference()
+    {
+        $a = [];
+        $a[] = &$a;
+
+        $exception = NotCallableException::fromInvalidCallable($a);
+
+        $this->assertStringContainsString('is not a callable', $exception->getMessage());
+    }
+
+    /**
+     * @test
+     */
+    #[\PHPUnit\Framework\Attributes\Test]
+    public function handles_circular_array_reference_as_container_entry()
+    {
+        $a = [];
+        $a[] = &$a;
+
+        $exception = NotCallableException::fromInvalidCallable($a, true);
+
+        $this->assertStringContainsString('is neither a callable nor a valid container entry', $exception->getMessage());
+    }
+}