Error Handling: gracefully handle missing livekit service url in config

locales/en/app.json

@@ -85,7 +85,8 @@
     "insufficient_capacity": "Insufficient capacity",
     "insufficient_capacity_description": "The server has reached its maximum capacity and you cannot join the call at this time. Try again later, or contact your server admin if the problem persists.",
     "open_elsewhere": "Opened in another tab",
-    "open_elsewhere_description": "{{brand}} has been opened in another tab. If that doesn't sound right, try reloading the page."
+    "open_elsewhere_description": "{{brand}} has been opened in another tab. If that doesn't sound right, try reloading the page.",
+    "unexpected_ec_error": "An unexpected error occurred (<0>Error Code:</0> <1>{{ errorCode }}</1>). Please contact your server administrator."
   },
   "group_call_loader": {
     "banned_body": "You have been banned from the room.",

src/RichError.tsx

@@ -6,13 +6,14 @@ Please see LICENSE in the repository root for full details.
 */
 
 import { type FC, type ReactNode } from "react";
-import { useTranslation } from "react-i18next";
+import { Trans, useTranslation } from "react-i18next";
 import {
   HostIcon,
   PopOutIcon,
 } from "@vector-im/compound-design-tokens/assets/web/icons";
 
 import { ErrorView } from "./ErrorView";
+import { type ElementCallError, type ErrorCode } from "./utils/ec-errors.ts";
 
 /**
  * An error consisting of a terse message to be logged to the console and a
@@ -65,3 +66,33 @@ export class InsufficientCapacityError extends RichError {
     super("Insufficient server capacity", <InsufficientCapacity />);
   }
 }
+
+type ECErrorProps = {
+  errorCode: ErrorCode;
+};
+
+const GenericECError: FC<{ errorCode: ErrorCode }> = ({
+  errorCode,
+}: ECErrorProps) => {
+  const { t } = useTranslation();
+
+  return (
+    <ErrorView Icon={HostIcon} title={t("error.generic")}>
+      <p>
+        <Trans
+          i18nKey="error.unexpected_ec_error"
+          components={[<b />, <code />]}
+          values={{ errorCode }}
+        />
+      </p>
+    </ErrorView>
+  );
+};
+
+export class ElementCallRichError extends RichError {
+  public ecError: ElementCallError;
+  public constructor(ecError: ElementCallError) {
+    super(ecError.message, <GenericECError errorCode={ecError.code} />);
+    this.ecError = ecError;
+  }
+}

src/room/GroupCallView.tsx

@@ -16,8 +16,8 @@ import {
 } from "react";
 import { type MatrixClient } from "matrix-js-sdk/src/client";
 import {
-  Room,
   isE2EESupported as isE2EESupportedBrowser,
+  Room,
 } from "livekit-client";
 import { logger } from "matrix-js-sdk/src/logger";
 import { type MatrixRTCSession } from "matrix-js-sdk/src/matrixrtc/MatrixRTCSession";
@@ -62,6 +62,7 @@ import { useLatest } from "../useLatest";
 import { usePageTitle } from "../usePageTitle";
 import { ErrorView } from "../ErrorView";
 import { ConnectionLostError, ElementCallError } from "../utils/ec-errors.ts";
+import { ElementCallRichError } from "../RichError.tsx";
 
 declare global {
   interface Window {
@@ -166,6 +167,22 @@ export const GroupCallView: FC<Props> = ({
   const latestDevices = useLatest(deviceContext);
   const latestMuteStates = useLatest(muteStates);
 
+  const enterRTCSessionOrError = async (
+    rtcSession: MatrixRTCSession,
+    perParticipantE2EE: boolean,
+  ): Promise<void> => {
+    try {
+      await enterRTCSession(rtcSession, perParticipantE2EE);
+    } catch (e) {
+      if (e instanceof ElementCallError) {
+        // e.code === ErrorCode.MISSING_LIVE_KIT_SERVICE_URL)
+        setEnterRTCError(e);
+      } else {
+        logger.error(`Unknown Error while entering RTC session`, e);
+      }
+    }
+  };
+
   useEffect(() => {
     const defaultDeviceSetup = async ({
       audioInput,
@@ -215,7 +232,7 @@ export const GroupCallView: FC<Props> = ({
               await defaultDeviceSetup(
                 ev.detail.data as unknown as JoinCallData,
               );
-              await enterRTCSession(rtcSession, perParticipantE2EE);
+              await enterRTCSessionOrError(rtcSession, perParticipantE2EE);
               widget.api.transport.reply(ev.detail, {});
             })().catch((e) => {
               logger.error("Error joining RTC session", e);
@@ -228,13 +245,13 @@ export const GroupCallView: FC<Props> = ({
         } else {
           // No lobby and no preload: we enter the rtc session right away
           (async (): Promise<void> => {
-            await enterRTCSession(rtcSession, perParticipantE2EE);
+            await enterRTCSessionOrError(rtcSession, perParticipantE2EE);
           })().catch((e) => {
             logger.error("Error joining RTC session", e);
           });
         }
       } else {
-        void enterRTCSession(rtcSession, perParticipantE2EE);
+        void enterRTCSessionOrError(rtcSession, perParticipantE2EE);
       }
     }
   }, [
@@ -248,6 +265,9 @@ export const GroupCallView: FC<Props> = ({
   ]);
 
   const [left, setLeft] = useState(false);
+  const [enterRTCError, setEnterRTCError] = useState<ElementCallError | null>(
+    null,
+  );
   const navigate = useNavigate();
 
   const onLeave = useCallback(
@@ -348,8 +368,8 @@ export const GroupCallView: FC<Props> = ({
       const onReconnect = useCallback(() => {
         setLeft(false);
         resetError();
-        enterRTCSession(rtcSession, perParticipantE2EE).catch((e) => {
-          logger.error("Error re-entering RTC session on reconnect", e);
+        enterRTCSessionOrError(rtcSession, perParticipantE2EE).catch((e) => {
+          logger.error("Error re-entering RTC session", e);
         });
       }, [resetError]);
 
@@ -398,7 +418,9 @@ export const GroupCallView: FC<Props> = ({
         client={client}
         matrixInfo={matrixInfo}
         muteStates={muteStates}
-        onEnter={() => void enterRTCSession(rtcSession, perParticipantE2EE)}
+        onEnter={() =>
+          void enterRTCSessionOrError(rtcSession, perParticipantE2EE)
+        }
         confineToRoom={confineToRoom}
         hideHeader={hideHeader}
         participantCount={participantCount}
@@ -408,7 +430,14 @@ export const GroupCallView: FC<Props> = ({
   );
 
   let body: ReactNode;
-  if (isJoined) {
+  if (enterRTCError) {
+    // If an ElementCallError was recorded, then create a component that will fail to render and throw
+    // an ElementCallRichError error. This will then be handled by the ErrorBoundary component.
+    const ErrorComponent = (): ReactNode => {
+      throw new ElementCallRichError(enterRTCError);
+    };
+    body = <ErrorComponent />;
+  } else if (isJoined) {
     body = (
       <>
         {shareModal}

src/rtcSessionHelpers.test.ts

@@ -13,6 +13,7 @@ import EventEmitter from "events";
 import { enterRTCSession, leaveRTCSession } from "../src/rtcSessionHelpers";
 import { mockConfig } from "./utils/test";
 import { ElementWidgetActions, widget } from "./widget";
+import { ErrorCode } from "./utils/ec-errors.ts";
 
 const actualWidget = await vi.hoisted(async () => vi.importActual("./widget"));
 vi.mock("./widget", () => ({
@@ -137,3 +138,50 @@ test("leaveRTCSession doesn't close the widget on a fatal error", async () => {
     expect.anything(),
   );
 });
+
+test("It fails with configuration error if no live kit url config is set in fallback", async () => {
+  mockConfig({});
+  vi.spyOn(AutoDiscovery, "getRawClientConfig").mockResolvedValue({});
+
+  const mockedSession = vi.mocked({
+    room: {
+      roomId: "roomId",
+      client: {
+        getDomain: vi.fn().mockReturnValue("example.org"),
+      },
+    },
+    memberships: [],
+    getFocusInUse: vi.fn(),
+    joinRoomSession: vi.fn(),
+  }) as unknown as MatrixRTCSession;
+
+  await expect(enterRTCSession(mockedSession, false)).rejects.toThrowError(
+    expect.objectContaining({ code: ErrorCode.MISSING_LIVE_KIT_SERVICE_URL }),
+  );
+});
+
+test("It should not fail with configuration error if homeserver config has livekit url but not fallback", async () => {
+  mockConfig({});
+  vi.spyOn(AutoDiscovery, "getRawClientConfig").mockResolvedValue({
+    "org.matrix.msc4143.rtc_foci": [
+      {
+        type: "livekit",
+        livekit_service_url: "http://my-well-known-service-url.com",
+      },
+    ],
+  });
+
+  const mockedSession = vi.mocked({
+    room: {
+      roomId: "roomId",
+      client: {
+        getDomain: vi.fn().mockReturnValue("example.org"),
+      },
+    },
+    memberships: [],
+    getFocusInUse: vi.fn(),
+    joinRoomSession: vi.fn(),
+  }) as unknown as MatrixRTCSession;
+
+  await enterRTCSession(mockedSession, false);
+});

src/rtcSessionHelpers.ts

@@ -8,16 +8,17 @@ Please see LICENSE in the repository root for full details.
 import { type MatrixRTCSession } from "matrix-js-sdk/src/matrixrtc/MatrixRTCSession";
 import { logger } from "matrix-js-sdk/src/logger";
 import {
-  type LivekitFocus,
-  type LivekitFocusActive,
   isLivekitFocus,
   isLivekitFocusConfig,
+  type LivekitFocus,
+  type LivekitFocusActive,
 } from "matrix-js-sdk/src/matrixrtc/LivekitFocus";
 import { AutoDiscovery } from "matrix-js-sdk/src/autodiscovery";
 
 import { PosthogAnalytics } from "./analytics/PosthogAnalytics";
 import { Config } from "./config/Config";
-import { ElementWidgetActions, type WidgetHelpers, widget } from "./widget";
+import { ElementWidgetActions, widget, type WidgetHelpers } from "./widget";
+import { ElementCallError, ErrorCode } from "./utils/ec-errors.ts";
 
 const FOCI_WK_KEY = "org.matrix.msc4143.rtc_foci";
 
@@ -80,9 +81,10 @@ async function makePreferredLivekitFoci(
   }
 
   if (preferredFoci.length === 0)
-    throw new Error(
+    throw new ElementCallError(
       `No livekit_service_url is configured so we could not create a focus.
     Currently we skip computing a focus based on other users in the room.`,
+      ErrorCode.MISSING_LIVE_KIT_SERVICE_URL,
     );
   return Promise.resolve(preferredFoci);