fix(saveObjects-error-msg): fix PR

Author: chloelbn

src/Exceptions/InvalidArgumentObjectsException.php

@@ -2,11 +2,20 @@
 
 namespace Algolia\AlgoliaSearch\Exceptions;
 
+use Throwable;
+
 final class InvalidArgumentObjectsException extends AlgoliaException
 {
+    /**
+     * InvalidArgumentObjectsException constructor.
+     *
+     * @param string    $message  [optional] The Exception message to throw
+     * @param int       $code     [optional] The Exception code
+     * @param throwable $previous [optional] The previous throwable used for the exception chaining
+     */
     public function __construct($message = '', $code = 0, $previous = null)
     {
-        if (!$message) {
+        if ('' === $message) {
             $message = 'Please provide an array of objects instead of a single object.';
         }