Conform more of the code base to strict null checking (#10147)

* Conform more of the code base to strict null checking

* More strict fixes

* More strict work

* Fix missing optional type

* Iterate

src/utils/dm/createDmLocalRoom.ts

@@ -31,10 +31,10 @@ import { determineCreateRoomEncryptionOption, Member } from "../../../src/utils/
  * @returns {Promise<LocalRoom>} Resolves to the new local room
  */
 export async function createDmLocalRoom(client: MatrixClient, targets: Member[]): Promise<LocalRoom> {
-    const userId = client.getUserId();
+    const userId = client.getUserId()!;
 
     const localRoom = new LocalRoom(LOCAL_ROOM_ID_PREFIX + client.makeTxnId(), client, userId);
-    const events = [];
+    const events: MatrixEvent[] = [];
 
     events.push(
         new MatrixEvent({
@@ -121,7 +121,7 @@ export async function createDmLocalRoom(client: MatrixClient, targets: Member[])
     localRoom.updateMyMembership("join");
     localRoom.addLiveEvents(events);
     localRoom.currentState.setStateEvents(events);
-    localRoom.name = localRoom.getDefaultRoomName(client.getUserId());
+    localRoom.name = localRoom.getDefaultRoomName(client.getUserId()!);
     client.store.storeRoom(localRoom);
 
     return localRoom;

src/utils/dm/startDm.ts

@@ -35,7 +35,7 @@ export async function startDm(client: MatrixClient, targets: Member[], showSpinn
     const targetIds = targets.map((t) => t.userId);
 
     // Check if there is already a DM with these people and reuse it if possible.
-    let existingRoom: Room;
+    let existingRoom: Room | undefined;
     if (targetIds.length === 1) {
         existingRoom = findDMForUser(client, targetIds[0]);
     } else {
@@ -66,12 +66,15 @@ export async function startDm(client: MatrixClient, targets: Member[], showSpinn
     }
 
     if (targetIds.length > 1) {
-        createRoomOptions.createOpts = targetIds.reduce(
+        createRoomOptions.createOpts = targetIds.reduce<{
+            invite_3pid: IInvite3PID[];
+            invite: string[];
+        }>(
             (roomOptions, address) => {
                 const type = getAddressType(address);
                 if (type === "email") {
                     const invite: IInvite3PID = {
-                        id_server: client.getIdentityServerUrl(true),
+                        id_server: client.getIdentityServerUrl(true)!,
                         medium: "email",
                         address,
                     };