You could force to add "http" or "https" before the canonical URL (in order to avoid replicate concerning the http and https Variation of an internet site). Ex: if you end up picking to force https with the canonical URL, the canonical URL of the page is going to be https://www.presta-addons-modules.com/en/opencart-seo-automatic-google-rich-snippets-json-ld-integration-opengraph-twitter-tags-schemaorg.html