Add safety around missing topics and space settings (#8957)

Author: turt2live

src/components/views/spaces/SpaceSettingsGeneralTab.tsx

@@ -48,7 +48,7 @@ const SpaceSettingsGeneralTab = ({ matrixClient: cli, space, onFinished }: IProp
     const canSetName = space.currentState.maySendStateEvent(EventType.RoomName, userId);
     const nameChanged = name !== space.name;
 
-    const currentTopic = getTopic(space).text;
+    const currentTopic = getTopic(space)?.text;
     const [topic, setTopic] = useState<string>(currentTopic);
     const canSetTopic = space.currentState.maySendStateEvent(EventType.RoomTopic, userId);
     const topicChanged = topic !== currentTopic;

src/hooks/room/useTopic.ts

@@ -21,10 +21,11 @@ import { Room } from "matrix-js-sdk/src/models/room";
 import { RoomStateEvent } from "matrix-js-sdk/src/models/room-state";
 import { parseTopicContent, TopicState } from "matrix-js-sdk/src/content-helpers";
 import { MRoomTopicEventContent } from "matrix-js-sdk/src/@types/topic";
+import { Optional } from "matrix-events-sdk";
 
 import { useTypedEventEmitter } from "../useEventEmitter";
 
-export const getTopic = (room: Room) => {
+export const getTopic = (room: Room): Optional<TopicState> => {
     const content: MRoomTopicEventContent = room?.currentState?.getStateEvents(EventType.RoomTopic, "")?.getContent();
     return !!content ? parseTopicContent(content) : null;
 };