Fix a crash where a name could unexpectedly be an empty list

src/components/structures/RoomSubList.js

@@ -37,6 +37,42 @@ import toRem from "../../utils/rem";
 // turn this on for drop & drag console debugging galore
 const debug = false;
 
+class RoomTileErrorBoundary extends React.PureComponent {
+    constructor(props) {
+        super(props);
+
+        this.state = {
+            error: null,
+        };
+    }
+
+    static getDerivedStateFromError(error) {
+        // Side effects are not permitted here, so we only update the state so
+        // that the next render shows an error message.
+        return { error };
+    }
+
+    componentDidCatch(error, { componentStack }) {
+        // Browser consoles are better at formatting output when native errors are passed
+        // in their own `console.error` invocation.
+        console.error(error);
+        console.error(
+            "The above error occured while React was rendering the following components:",
+            componentStack,
+        );
+    }
+
+    render() {
+        if (this.state.error) {
+            return (<div className="mx_RoomTile mx_RoomTileError">
+                {this.props.roomId}
+            </div>);
+        } else {
+            return this.props.children;
+        }
+    }
+}
+
 export default class RoomSubList extends React.PureComponent {
     static displayName = 'RoomSubList';
     static debug = debug;
@@ -208,7 +244,7 @@ export default class RoomSubList extends React.PureComponent {
     };
 
     makeRoomTile = (room) => {
-        return <RoomTile
+        return <RoomTileErrorBoundary roomId={room.roomId}><RoomTile
             room={room}
             roomSubList={this}
             tagName={this.props.tagName}
@@ -221,7 +257,7 @@ export default class RoomSubList extends React.PureComponent {
             refreshSubList={this._updateSubListCount}
             incomingCall={null}
             onClick={this.onRoomTileClick}
-        />;
+        /></RoomTileErrorBoundary>;
     };
 
     _onNotifBadgeClick = (e) => {

src/components/views/rooms/RoomTile.js

@@ -432,10 +432,9 @@ export default createReactClass({
         });
 
         let name = this.state.roomName;
-        if (name == undefined || name == null) name = '';
+        if (typeof name !== 'string') name = '';
         name = name.replace(":", ":\u200b"); // add a zero-width space to allow linewrapping after the colon
 
-
         let badge;
         if (badges) {
             const limitedCount = FormattingUtils.formatCount(notificationCount);