only add url field on sticker events (properly)

portal.go

@@ -3434,12 +3434,6 @@ func (portal *Portal) uploadMedia(intent *appservice.IntentAPI, data []byte, con
 	if file != nil {
 		file.URL = mxc.CUString()
 		content.File = file
-		// Sticker events require the URL field to be present https://spec.matrix.org/v1.9/client-server-api/#events-16
-		// This seems to affect only clients based on the Rust SDK on encrypted channels (like Element X)
-		isSticker := string(content.MsgType) == event.EventSticker.Type
-		if isSticker {
-			content.URL = mxc.CUString()
-		}
 	} else {
 		content.URL = mxc.CUString()
 	}
@@ -3506,6 +3500,13 @@ func (portal *Portal) convertMediaMessage(intent *appservice.IntentAPI, source *
 			return portal.makeMediaBridgeFailureMessage(info, fmt.Errorf("failed to upload media: %w", err), converted, nil, "")
 		}
 	}
+
+	// Sticker events require the URL field to be present https://spec.matrix.org/v1.9/client-server-api/#events-16
+        // This seems to affect only clients based on the Rust SDK on encrypted channels (like Element X)
+	if typeName == "sticker" && converted.Content.File != nil {
+		converted.Content.URL = converted.Content.File.URL
+	}
+
 	return converted
 }