app/post_metadata: add a type cast check for OpenGraph images (#19877)

* app/post_metadata: add a type cast check for OpenGraph images

* change log level

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/post_metadata.go

@@ -295,7 +295,13 @@ func (a *App) getImagesForPost(post *model.Post, imageURLs []string, isNewPost b
 			imageURLs = append(imageURLs, a.getImagesInMessageAttachments(post)...)
 
 		case model.PostEmbedOpengraph:
-			for _, image := range embed.Data.(*opengraph.OpenGraph).Images {
+			openGraph, ok := embed.Data.(*opengraph.OpenGraph)
+			if !ok {
+				mlog.Warn("Could not read the image data: the data could not be casted to OpenGraph",
+					mlog.String("post_id", post.Id), mlog.String("data type", fmt.Sprintf("%t", embed.Data)))
+				continue
+			}
+			for _, image := range openGraph.Images {
 				var imageURL string
 				if image.SecureURL != "" {
 					imageURL = image.SecureURL