Fixing error messages (#5995)

app/post.go

@@ -567,13 +567,13 @@ func GetOpenGraphMetadata(url string) *opengraph.OpenGraph {
 
 	res, err := httpClient.Get(url)
 	if err != nil {
-		l4g.Error(err.Error())
+		l4g.Error("GetOpenGraphMetadata request failed for url=%v with err=%v", url, err.Error())
 		return og
 	}
 	defer CloseBody(res)
 
 	if err := og.ProcessHTML(res.Body); err != nil {
-		l4g.Error(err.Error())
+		l4g.Error("GetOpenGraphMetadata processing failed for url=%v with err=%v", url, err.Error())
 	}
 
 	return og