Fix. Tests. Added verification of the argument type

Author: AntonV1211

tests/ApbctWP/HTTP/TestSFWFilesDownloader.php

@@ -50,6 +50,18 @@ protected function tearDown(): void
         $apbct = $this->apbctBackup;
     }
 
+    /**
+     * @test
+     */
+    public function testThrowsExceptionWhenInvalidServicePassed()
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Service must be an instance of');
+
+        // Pass an invalid object (not HTTPMultiRequestService)
+        new SFWFilesDownloader(new \stdClass());
+    }
+
     /**
      * @test
      */