[FIX] website_slides: fix error message display on upload

When uploading twice the same video for a channel, the error message displayed unhandled html.
We removed the html to avoid having to use $el.html() for better safety (and it should not happen often anyway).

addons/website_slides/controllers/main.py

@@ -764,7 +764,7 @@ class WebsiteSlides(WebsiteProfile):
             return preview
         existing_slide = Slide.search([('channel_id', '=', int(data['channel_id'])), ('document_id', '=', document_id)], limit=1)
         if existing_slide:
-            preview['error'] = _('This video already exists in this channel <a target="_blank" href="/slides/slide/%s">click here to view it </a>') % existing_slide.id
+            preview['error'] = _('This video already exists in this channel on the following slide: %s') % existing_slide.name
             return preview
         values = Slide._parse_document_url(data['url'], only_preview_fields=True)
         if values.get('error'):