diff --git a/frontend/stores/useLatestStateStore.ts b/frontend/stores/useLatestStateStore.ts
index 440e74072..8af99bed3 100644
--- a/frontend/stores/useLatestStateStore.ts
+++ b/frontend/stores/useLatestStateStore.ts
@@ -16,19 +16,19 @@ export function useLatestStateStore() {
 
   const latestState = computed(() => data.value)
 
-  async function refreshLatestState(): Promise<LatestStateData | undefined> {
+  async function refreshLatestState() {
     try {
       const res = await fetch<InternalGetLatestStateResponse>(
         API_PATH.LATEST_STATE,
       )
       if (!res.data) {
-        return undefined
+        return null
       }
       data.value = res.data
       return data.value
     }
     catch {
-      return undefined
+      return null
     }
   }
 
diff --git a/frontend/stores/useUserStore.ts b/frontend/stores/useUserStore.ts
index 08aed21a2..8011c8b47 100644
--- a/frontend/stores/useUserStore.ts
+++ b/frontend/stores/useUserStore.ts
@@ -27,7 +27,7 @@ export function useUserStore() {
     data.value = user
   }
 
-  async function getUser(): Promise<undefined | UserInfo> {
+  async function getUser() {
     try {
       const res = await fetch<InternalGetUserInfoResponse>(
         API_PATH.USER,
@@ -37,7 +37,7 @@ export function useUserStore() {
     }
     catch {
       setUser(undefined)
-      return undefined
+      return null
     }
   }