Added @throws CaptchaException annotation to insertBackground method in Image.php.

app/application/app/Captcha/Images/Image.php

@@ -24,6 +24,9 @@ final class Image implements ImageContract
         return imagesy($this->image);
     }
 
+    /**
+     * @throws CaptchaException
+     */
     public function insertBackground(string $pathToFile): ImageContract
     {
         list($backgroundWidth, $backgroundHeight) = getimagesize($pathToFile);