Conform more of the codebase to strictNullChecks (#10842)

src/createRoom.ts

@@ -30,7 +30,7 @@ import { logger } from "matrix-js-sdk/src/logger";
 
 import { MatrixClientPeg } from "./MatrixClientPeg";
 import Modal, { IHandle } from "./Modal";
-import { _t } from "./languageHandler";
+import { _t, UserFriendlyError } from "./languageHandler";
 import dis from "./dispatcher/dispatcher";
 import * as Rooms from "./Rooms";
 import { getAddressType } from "./UserAddress";
@@ -121,14 +121,23 @@ export default async function createRoom(opts: IOpts): Promise<string | null> {
             case "mx-user-id":
                 createOpts.invite = [opts.dmUserId];
                 break;
-            case "email":
+            case "email": {
+                const isUrl = MatrixClientPeg.get().getIdentityServerUrl(true);
+                if (!isUrl) {
+                    throw new UserFriendlyError(
+                        "Cannot invite user by email without an identity server. " +
+                            'You can connect to one under "Settings".',
+                    );
+                }
                 createOpts.invite_3pid = [
                     {
-                        id_server: MatrixClientPeg.get().getIdentityServerUrl(true),
+                        id_server: isUrl,
                         medium: "email",
                         address: opts.dmUserId,
                     },
                 ];
+                break;
+            }
         }
     }
     if (opts.dmUserId && createOpts.is_direct === undefined) {