product not saving – getting error (Warning: Invalid argument supplied for foreach() in /home/…./Validator/NotProtectedExtension.php on line 84)

while creating the new products its throwing below error

“Warning: Invalid argument supplied for foreach() in home/……/public_html/vendor/magento/module-media-storage/Model/File/Validator/NotProtectedExtension.php on line 84”

same issue with import option also.

    protected function _initProtectedFileExtensions()
{
    if (!$this->_protectedFileExtensions) {
        $extensions = $this->getProtectedFileExtensions();
        if (is_string($extensions)) {
            $extensions = explode(',', $extensions);
        }
        foreach ($extensions as &$ext) {
            $ext = strtolower(trim($ext));
        }
        $this->_protectedFileExtensions = (array)$extensions;
    }
    return $this;
}

Does anyone have idea about this issue?