From 8de4f27bcb92f2722c74d0398c921a3f291fc044 Mon Sep 17 00:00:00 2001
From: Marco Bartelt <marco.bartelt.ext@bwi.de>
Date: Wed, 7 Dec 2022 11:05:04 +0100
Subject: [PATCH] handles not existing RoomPowerLevels event gracefully

---
 src/components/views/settings/AddPrivilegedUsers.tsx   | 10 ++++++++++
 .../views/settings/AddPrivilegedUsers-test.tsx         | 10 +++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/components/views/settings/AddPrivilegedUsers.tsx b/src/components/views/settings/AddPrivilegedUsers.tsx
index cf9099c522c..f85699c7413 100644
--- a/src/components/views/settings/AddPrivilegedUsers.tsx
+++ b/src/components/views/settings/AddPrivilegedUsers.tsx
@@ -52,6 +52,16 @@ export const AddPrivilegedUsers: React.FC<AddPrivilegedUsersProps> = ({ room, de
         const userIds = getUserIdsFromCompletions(selectedUsers);
         const powerLevelEvent = room.currentState.getStateEvents(EventType.RoomPowerLevels, "");
 
+        // `RoomPowerLevels` event should exist, but technically it is not guaranteed.
+        if (powerLevelEvent === null) {
+            Modal.createDialog(ErrorDialog, {
+                title: _t("Error"),
+                description: _t("Failed to change power level"),
+            });
+
+            return;
+        }
+
         try {
             await client.setPowerLevel(room.roomId, userIds, powerLevel, powerLevelEvent);
             setSelectedUsers([]);
diff --git a/test/components/views/settings/AddPrivilegedUsers-test.tsx b/test/components/views/settings/AddPrivilegedUsers-test.tsx
index 21d1b6b0ca2..67258e47df8 100644
--- a/test/components/views/settings/AddPrivilegedUsers-test.tsx
+++ b/test/components/views/settings/AddPrivilegedUsers-test.tsx
@@ -17,11 +17,12 @@ import React from 'react';
 import { act, fireEvent, render, waitFor } from '@testing-library/react';
 import userEvent from "@testing-library/user-event";
 import { mocked } from "jest-mock";
-import { RoomMember } from "matrix-js-sdk/src/matrix";
+import { RoomMember, EventType } from "matrix-js-sdk/src/matrix";
 
 import {
     getMockClientWithEventEmitter,
     makeRoomWithStateEvents,
+    mkEvent,
 } from "../../../test-utils";
 import MatrixClientContext from '../../../../src/contexts/MatrixClientContext';
 import {
@@ -56,6 +57,13 @@ describe('<AddPrivilegedUsers />', () => {
 
         return member;
     };
+    (room.currentState.getStateEvents as unknown) = (_eventType: string, _stateKey: string) => {
+        return mkEvent({
+            type: EventType.RoomPowerLevels,
+            content: {},
+            user: 'user_id',
+        });
+    };
 
     const getComponent = () =>
         <MatrixClientContext.Provider value={mockClient}>