In class SimpleImage the php internal function imagecreatefromstring() raises php warnings if the data is invalid:
E_WARNING: imagecreatefromstring(): Data is not in a recognized format
The function is used in two methods: fromDataUri() and fromFile()
Please change to @imagecreatefromstring() and throw an exception if result is false (see https://www.php.net/manual/en/function.imagecreatefromstring.php)
Thanks!