test: update recurrence expansion test + fix TS/Lint errors

lib/jmap/client.ts

@@ -6096,6 +6096,7 @@ export class JMAPClient implements IJMAPClient {
   private wsReconnectAttempts: number = 0;
   private wsConsecutiveFailures: number = 0;
   private wsPermanentlyDisabled: boolean = false;
+  private _statesPromise: Promise<void> | null = null;
   private wsHeartbeatTimer: NodeJS.Timeout | null = null;
   private lastWSActivity: number = 0;
 
@@ -6177,7 +6178,7 @@ export class JMAPClient implements IJMAPClient {
       // entirely: SSE only streams changes from the moment it connects
       // onward (no catch-up on connect), so the one thing that CAN catch up
       // is a diff against a state snapshot taken before the gap started.
-      void this.fetchCurrentStates();
+      this._statesPromise = this.fetchCurrentStates();
       // Not confirmed either way whether this server's WebSocket push fans
       // out to shared/secondary accounts or, like Stalwart's SSE, covers the
       // primary account only - keep the same secondary poll running under
@@ -6321,7 +6322,7 @@ export class JMAPClient implements IJMAPClient {
    * original 31s-worst-case ladder did.
    */
   private async reconcileAfterWebSocketFallback(): Promise<void> {
-    await this._stateSnapshotPromise;
+    await this._statesPromise;
     await this.checkForStateChanges();
 
     const eventSourceUrl = this.getEventSourceUrl();