Update connection.ts

Author: bramkragten

lib/connection.ts

@@ -301,7 +301,10 @@ export class Connection {
   async subscribeMessage<Result>(
     callback: (result: Result) => void,
     subscribeMessage: MessageBase,
-    options?: { resubscribe?: boolean; preCheck?: () => Promise<boolean> },
+    options?: {
+      resubscribe?: boolean;
+      preCheck?: () => boolean | Promise<boolean>;
+    },
   ): Promise<SubscriptionUnsubscribe> {
     if (this._queuedMessages) {
       await new Promise((resolve, reject) => {