diff --git a/extensions/feishu/src/sequential-queue.test.ts b/extensions/feishu/src/sequential-queue.test.ts
index a0ea3dfd4d6..2f4d6971860 100644
--- a/extensions/feishu/src/sequential-queue.test.ts
+++ b/extensions/feishu/src/sequential-queue.test.ts
@@ -2,10 +2,13 @@ import { describe, expect, it } from "vitest";
 import { createSequentialQueue } from "./sequential-queue.js";
 
 function createDeferred() {
-  let resolve!: () => void;
+  let resolve: (() => void) | undefined;
   const promise = new Promise<void>((res) => {
     resolve = res;
   });
+  if (!resolve) {
+    throw new Error("Expected deferred resolver to be initialized");
+  }
   return { promise, resolve };
 }
 
diff --git a/ui/src/ui/controllers/assistant-identity.test.ts b/ui/src/ui/controllers/assistant-identity.test.ts
index 2b18d927da4..f67126723ed 100644
--- a/ui/src/ui/controllers/assistant-identity.test.ts
+++ b/ui/src/ui/controllers/assistant-identity.test.ts
@@ -5,10 +5,13 @@ import { loadLocalAssistantIdentity } from "../storage.ts";
 import { loadAssistantIdentity, setAssistantAvatarOverride } from "./assistant-identity.ts";
 
 function createDeferred<T>() {
-  let resolve!: (value: T) => void;
+  let resolve: ((value: T) => void) | undefined;
   const promise = new Promise<T>((next) => {
     resolve = next;
   });
+  if (!resolve) {
+    throw new Error("Expected deferred resolver to be initialized");
+  }
   return { promise, resolve };
 }
 
diff --git a/ui/src/ui/controllers/chat.test.ts b/ui/src/ui/controllers/chat.test.ts
index 85241cc0de8..4c165f4e5a4 100644
--- a/ui/src/ui/controllers/chat.test.ts
+++ b/ui/src/ui/controllers/chat.test.ts
@@ -39,12 +39,15 @@ afterEach(() => {
 });
 
 function createDeferred<T>() {
-  let resolve!: (value: T) => void;
-  let reject!: (reason?: unknown) => void;
+  let resolve: ((value: T) => void) | undefined;
+  let reject: ((reason?: unknown) => void) | undefined;
   const promise = new Promise<T>((res, rej) => {
     resolve = res;
     reject = rej;
   });
+  if (!resolve || !reject) {
+    throw new Error("Expected deferred callbacks to be initialized");
+  }
   return { promise, resolve, reject };
 }