From 5d0047aebe105648dba90f440cbd9eb765fe778b Mon Sep 17 00:00:00 2001
From: fkwp <github-fkwp@w4ve.de>
Date: Wed, 10 Jun 2026 12:49:28 +0200
Subject: [PATCH] Use error.cause instead of name to detect sticky-events
 failure

---
 src/room/GroupCallView.test.tsx | 28 ++++++++++++++++++++--------
 src/room/GroupCallView.tsx      | 16 +++++++++++-----
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/room/GroupCallView.test.tsx b/src/room/GroupCallView.test.tsx
index 92c27077f..53b18cde0 100644
--- a/src/room/GroupCallView.test.tsx
+++ b/src/room/GroupCallView.test.tsx
@@ -19,7 +19,12 @@ import {
   vitest,
 } from "vitest";
 import { render, waitFor, screen, act } from "@testing-library/react";
-import { type MatrixClient, JoinRule, type RoomState } from "matrix-js-sdk";
+import {
+  type MatrixClient,
+  JoinRule,
+  type RoomState,
+  UnsupportedStickyEventsEndpointError,
+} from "matrix-js-sdk";
 import {
   MatrixRTCSessionEvent,
   type MatrixRTCSession,
@@ -410,19 +415,26 @@ test.skip("GroupCallView shows errors that occur during joining", async () => {
   screen.getByText("Call is not supported");
 });
 
-test("translates UnsupportedStickyEventsEndpointError to the StickyEventsRequiredError screen", async () => {
-  // Match the shape the SDK emits on
-  // MatrixRTCSessionEvent.MembershipManagerError when matrix_2_0 mode is
-  // configured but the homeserver does not advertise MSC4354.
-  const stickyError = new Error("Server does not support the sticky events");
-  stickyError.name = "UnsupportedStickyEventsEndpointError";
+test("translates wrapped UnsupportedStickyEventsEndpointError to the StickyEventsRequiredError screen", async () => {
+  // Mirror the shape the SDK emits: the MembershipManager scheduler wraps
+  // the original UnsupportedStickyEventsEndpointError in a generic Error
+  // but preserves the original on `.cause`.
+  const stickyError = new UnsupportedStickyEventsEndpointError(
+    "Server does not support the sticky events",
+    "sendStickyEvent",
+  );
+  const wrappedError = new Error(
+    "The MembershipManager shut down because of the end condition: " +
+      String(stickyError),
+    { cause: stickyError },
+  );
 
   const { rtcSession } = createGroupCallView(null, true, {
     withErrorBoundary: true,
   });
 
   await act(() =>
-    rtcSession.emit(MatrixRTCSessionEvent.MembershipManagerError, stickyError),
+    rtcSession.emit(MatrixRTCSessionEvent.MembershipManagerError, wrappedError),
   );
 
   await screen.findByText("Homeserver does not support Matrix 2.0 calls");
diff --git a/src/room/GroupCallView.tsx b/src/room/GroupCallView.tsx
index 0879efda8..09ea15be3 100644
--- a/src/room/GroupCallView.tsx
+++ b/src/room/GroupCallView.tsx
@@ -13,7 +13,12 @@ import {
   useMemo,
   useState,
 } from "react";
-import { type MatrixClient, JoinRule, type Room } from "matrix-js-sdk";
+import {
+  type MatrixClient,
+  JoinRule,
+  type Room,
+  UnsupportedStickyEventsEndpointError,
+} from "matrix-js-sdk";
 import {
   Room as LivekitRoom,
   isE2EESupported as isE2EESupportedBrowser,
@@ -164,12 +169,13 @@ export const GroupCallView: FC<Props> = ({
     rtcSession,
     MatrixRTCSessionEvent.MembershipManagerError,
     (error) => {
-      // The SDK throws this typed error when matrix_rtc_mode=matrix_2_0 is in
-      // effect but the homeserver does not advertise MSC4354 (sticky events).
-      // Surface the actual cause instead of a generic connection-lost screen.
+      // When matrix_rtc_mode=matrix_2_0 is in effect but the homeserver does
+      // not advertise MSC4354 (sticky events), the SDK throws an
+      // `UnsupportedStickyEventsEndpointError`. The MembershipManager
+      // scheduler wraps it and exposes the original via `.cause`.
       if (
         error instanceof Error &&
-        error.name === "UnsupportedStickyEventsEndpointError"
+        error.cause instanceof UnsupportedStickyEventsEndpointError
       ) {
         setExternalError(new StickyEventsRequiredError());
       } else {