shieldStatusForRoom: guard against client shutdown (#11957)

If `shieldStatusForRoom` races against a logout operation, then some of the
(many) crypto operations that it does can fail. Catch the error and handle it
gracefully.

src/utils/ShieldUtils.ts

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { MatrixClient, Room } from "matrix-js-sdk/src/matrix";
+import { ClientStoppedError, MatrixClient, Room } from "matrix-js-sdk/src/matrix";
 import { logger } from "matrix-js-sdk/src/logger";
 
 import DMRoomMap from "./DMRoomMap";
@@ -32,6 +32,7 @@ export async function shieldStatusForRoom(client: MatrixClient, room: Room): Pro
         return E2EStatus.Warning;
     }
 
+    try {
         const members = (await room.getEncryptionTargetMembers()).map(({ userId }) => userId);
         const inDMMap = !!DMRoomMap.shared().getUserIdForRoomId(room.roomId);
 
@@ -76,4 +77,14 @@ export async function shieldStatusForRoom(client: MatrixClient, room: Room): Pro
         }
 
         return unverified.length === 0 ? E2EStatus.Verified : E2EStatus.Normal;
+    } catch (e) {
+        if (!(e instanceof ClientStoppedError)) {
+            throw e;
+        }
+
+        // The client has been stopped while we were figuring out what to do. Catch the exception to stop it being
+        // logged. It probably doesn't really matter what we return.
+        logger.warn("shieldStatusForRoom: client stopped");
+        return E2EStatus.Normal;
+    }
 }