Improve quality of Typescript types (#10742)

src/autocomplete/AutocompleteProvider.tsx

@@ -36,8 +36,8 @@ export interface IAutocompleteOptions {
 }
 
 export default abstract class AutocompleteProvider {
-    public commandRegex: RegExp;
-    public forcedCommandRegex: RegExp;
+    public commandRegex?: RegExp;
+    public forcedCommandRegex?: RegExp;
 
     protected renderingType: TimelineRenderingType = TimelineRenderingType.Room;
 

src/autocomplete/QueryMatcher.ts

@@ -47,7 +47,7 @@ interface IOptions<T extends {}> {
  */
 export default class QueryMatcher<T extends {}> {
     private _options: IOptions<T>;
-    private _items: Map<string, { object: T; keyWeight: number }[]>;
+    private _items = new Map<string, { object: T; keyWeight: number }[]>();
 
     public constructor(objects: T[], options: IOptions<T> = { keys: [] }) {
         this._options = options;

src/autocomplete/UserProvider.tsx

@@ -44,7 +44,7 @@ const FORCED_USER_REGEX = /[^/,:; \t\n]\S*/g;
 
 export default class UserProvider extends AutocompleteProvider {
     public matcher: QueryMatcher<RoomMember>;
-    public users: RoomMember[] | null;
+    public users?: RoomMember[];
     public room: Room;
 
     public constructor(room: Room, renderingType?: TimelineRenderingType) {
@@ -98,7 +98,7 @@ export default class UserProvider extends AutocompleteProvider {
         if (state.roomId !== this.room.roomId) return;
 
         // blow away the users cache
-        this.users = null;
+        this.users = undefined;
     };
 
     public async getCompletions(