diff --git a/packages/frontend/src/account.ts b/packages/frontend/src/account.ts
index 1e5f38cf1c..25af298910 100644
--- a/packages/frontend/src/account.ts
+++ b/packages/frontend/src/account.ts
@@ -26,6 +26,11 @@ export const $i = accountData ? reactive(JSON.parse(accountData) as Account) : n
 export const iAmModerator = $i != null && ($i.isAdmin === true || $i.isModerator === true);
 export const iAmAdmin = $i != null && $i.isAdmin;
 
+export function signinRequired() {
+	if ($i == null) throw new Error('signin required');
+	return $i;
+}
+
 export let notesCount = $i == null ? 0 : $i.notesCount;
 export function incNotesCount() {
 	notesCount++;
diff --git a/packages/frontend/src/pages/my-lists/index.vue b/packages/frontend/src/pages/my-lists/index.vue
index 0abfb15d98..14e2315843 100644
--- a/packages/frontend/src/pages/my-lists/index.vue
+++ b/packages/frontend/src/pages/my-lists/index.vue
@@ -19,7 +19,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 			<div v-if="items.length > 0" class="_gaps">
 				<MkA v-for="list in items" :key="list.id" class="_panel" :class="$style.list" :to="`/my/lists/${ list.id }`">
-					<div style="margin-bottom: 4px;">{{ list.name }} <span :class="$style.nUsers">({{ i18n.t('nUsers', { n: `${list.userIds.length}/${$i?.policies['userEachUserListsLimit']}` }) }})</span></div>
+					<div style="margin-bottom: 4px;">{{ list.name }} <span :class="$style.nUsers">({{ i18n.t('nUsers', { n: `${list.userIds.length}/${$i.policies['userEachUserListsLimit']}` }) }})</span></div>
 					<MkAvatars :userIds="list.userIds" :limit="10"/>
 				</MkA>
 			</div>
@@ -37,7 +37,9 @@ import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import { userListsCache } from '@/cache.js';
 import { infoImageUrl } from '@/instance.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
+
+const $i = signinRequired();
 
 const items = computed(() => userListsCache.value.value ?? []);
 
diff --git a/packages/frontend/src/pages/my-lists/list.vue b/packages/frontend/src/pages/my-lists/list.vue
index cf9da02868..482fdcd8f2 100644
--- a/packages/frontend/src/pages/my-lists/list.vue
+++ b/packages/frontend/src/pages/my-lists/list.vue
@@ -25,7 +25,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 			<MkFolder defaultOpen>
 				<template #label>{{ i18n.ts.members }}</template>
-				<template #caption>{{ i18n.t('nUsers', { n: `${list.userIds.length}/${$i?.policies['userEachUserListsLimit']}` }) }}</template>
+				<template #caption>{{ i18n.t('nUsers', { n: `${list.userIds.length}/${$i.policies['userEachUserListsLimit']}` }) }}</template>
 
 				<div class="_gaps_s">
 					<MkButton rounded primary style="margin: 0 auto;" @click="addUser()">{{ i18n.ts.addUser }}</MkButton>
@@ -66,10 +66,12 @@ import MkSwitch from '@/components/MkSwitch.vue';
 import MkFolder from '@/components/MkFolder.vue';
 import MkInput from '@/components/MkInput.vue';
 import { userListsCache } from '@/cache.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { defaultStore } from '@/store.js';
 import MkPagination from '@/components/MkPagination.vue';
 
+const $i = signinRequired();
+
 const {
 	enableInfiniteScroll,
 } = defaultStore.reactiveState;
diff --git a/packages/frontend/src/pages/settings/2fa.qrdialog.vue b/packages/frontend/src/pages/settings/2fa.qrdialog.vue
index 4641b49103..3d7bb06da2 100644
--- a/packages/frontend/src/pages/settings/2fa.qrdialog.vue
+++ b/packages/frontend/src/pages/settings/2fa.qrdialog.vue
@@ -110,7 +110,9 @@ import * as os from '@/os.js';
 import MkFolder from '@/components/MkFolder.vue';
 import MkInfo from '@/components/MkInfo.vue';
 import { confetti } from '@/scripts/confetti.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
+
+const $i = signinRequired();
 
 defineProps<{
 	twoFactorData: {
@@ -151,7 +153,7 @@ function downloadBackupCodes() {
 		const txtBlob = new Blob([backupCodes.value.join('\n')], { type: 'text/plain' });
 		const dummya = document.createElement('a');
 		dummya.href = URL.createObjectURL(txtBlob);
-		dummya.download = `${$i?.username}-2fa-backup-codes.txt`;
+		dummya.download = `${$i.username}-2fa-backup-codes.txt`;
 		dummya.click();
 	}
 }
diff --git a/packages/frontend/src/pages/settings/2fa.vue b/packages/frontend/src/pages/settings/2fa.vue
index 4c165ef4ee..35331738fd 100644
--- a/packages/frontend/src/pages/settings/2fa.vue
+++ b/packages/frontend/src/pages/settings/2fa.vue
@@ -80,9 +80,11 @@ import MkSwitch from '@/components/MkSwitch.vue';
 import FormSection from '@/components/form/section.vue';
 import MkFolder from '@/components/MkFolder.vue';
 import * as os from '@/os.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { i18n } from '@/i18n.js';
 
+const $i = signinRequired();
+
 // メモ: 各エンドポイントはmeUpdatedを発行するため、refreshAccountは不要
 
 withDefaults(defineProps<{
@@ -91,7 +93,7 @@ withDefaults(defineProps<{
 	first: false,
 });
 
-const usePasswordLessLogin = computed(() => $i?.usePasswordLessLogin ?? false);
+const usePasswordLessLogin = computed(() => $i.usePasswordLessLogin ?? false);
 
 async function registerTOTP(): Promise<void> {
 	const auth = await os.authenticateDialog();
diff --git a/packages/frontend/src/pages/settings/avatar-decoration.decoration.vue b/packages/frontend/src/pages/settings/avatar-decoration.decoration.vue
index 9c95b5547e..29586ad5f1 100644
--- a/packages/frontend/src/pages/settings/avatar-decoration.decoration.vue
+++ b/packages/frontend/src/pages/settings/avatar-decoration.decoration.vue
@@ -16,7 +16,9 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 <script lang="ts" setup>
 import { } from 'vue';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
+
+const $i = signinRequired();
 
 const props = defineProps<{
 	active?: boolean;
diff --git a/packages/frontend/src/pages/settings/avatar-decoration.dialog.vue b/packages/frontend/src/pages/settings/avatar-decoration.dialog.vue
index 329ab4d47a..4cd0dd10e6 100644
--- a/packages/frontend/src/pages/settings/avatar-decoration.dialog.vue
+++ b/packages/frontend/src/pages/settings/avatar-decoration.dialog.vue
@@ -51,7 +51,9 @@ import MkModalWindow from '@/components/MkModalWindow.vue';
 import MkSwitch from '@/components/MkSwitch.vue';
 import { i18n } from '@/i18n.js';
 import MkRange from '@/components/MkRange.vue';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
+
+const $i = signinRequired();
 
 const props = defineProps<{
 	usingIndex: number | null;
diff --git a/packages/frontend/src/pages/settings/avatar-decoration.vue b/packages/frontend/src/pages/settings/avatar-decoration.vue
index 6551fc917e..eb25f25ec8 100644
--- a/packages/frontend/src/pages/settings/avatar-decoration.vue
+++ b/packages/frontend/src/pages/settings/avatar-decoration.vue
@@ -51,10 +51,12 @@ import XDecoration from './avatar-decoration.decoration.vue';
 import MkButton from '@/components/MkButton.vue';
 import * as os from '@/os.js';
 import { i18n } from '@/i18n.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import MkInfo from '@/components/MkInfo.vue';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 
+const $i = signinRequired();
+
 const loading = ref(true);
 const avatarDecorations = ref<Misskey.entities.GetAvatarDecorationsResponse>([]);
 
diff --git a/packages/frontend/src/pages/settings/drive.vue b/packages/frontend/src/pages/settings/drive.vue
index 7857cf7125..e3a7b8ca80 100644
--- a/packages/frontend/src/pages/settings/drive.vue
+++ b/packages/frontend/src/pages/settings/drive.vue
@@ -71,7 +71,9 @@ import { defaultStore } from '@/store.js';
 import MkChart from '@/components/MkChart.vue';
 import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
+
+const $i = signinRequired();
 
 const fetching = ref(true);
 const usage = ref<number | null>(null);
diff --git a/packages/frontend/src/pages/settings/email.vue b/packages/frontend/src/pages/settings/email.vue
index 309e025ada..015152c50a 100644
--- a/packages/frontend/src/pages/settings/email.vue
+++ b/packages/frontend/src/pages/settings/email.vue
@@ -54,12 +54,14 @@ import MkInfo from '@/components/MkInfo.vue';
 import MkInput from '@/components/MkInput.vue';
 import MkSwitch from '@/components/MkSwitch.vue';
 import * as os from '@/os.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import { instance } from '@/instance.js';
 
-const emailAddress = ref($i!.email);
+const $i = signinRequired();
+
+const emailAddress = ref($i.email);
 
 const onChangeReceiveAnnouncementEmail = (v) => {
 	os.api('i/update', {
@@ -78,11 +80,11 @@ async function saveEmailAddress() {
 	});
 }
 
-const emailNotification_mention = ref($i!.emailNotificationTypes.includes('mention'));
-const emailNotification_reply = ref($i!.emailNotificationTypes.includes('reply'));
-const emailNotification_quote = ref($i!.emailNotificationTypes.includes('quote'));
-const emailNotification_follow = ref($i!.emailNotificationTypes.includes('follow'));
-const emailNotification_receiveFollowRequest = ref($i!.emailNotificationTypes.includes('receiveFollowRequest'));
+const emailNotification_mention = ref($i.emailNotificationTypes.includes('mention'));
+const emailNotification_reply = ref($i.emailNotificationTypes.includes('reply'));
+const emailNotification_quote = ref($i.emailNotificationTypes.includes('quote'));
+const emailNotification_follow = ref($i.emailNotificationTypes.includes('follow'));
+const emailNotification_receiveFollowRequest = ref($i.emailNotificationTypes.includes('receiveFollowRequest'));
 
 const saveNotificationSettings = () => {
 	os.api('i/update', {
diff --git a/packages/frontend/src/pages/settings/import-export.vue b/packages/frontend/src/pages/settings/import-export.vue
index 858983a214..d2dc3ea8bd 100644
--- a/packages/frontend/src/pages/settings/import-export.vue
+++ b/packages/frontend/src/pages/settings/import-export.vue
@@ -121,7 +121,7 @@ import { selectFile } from '@/scripts/select-file.js';
 import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import { $i } from '@/account.js';
-import { defaultStore } from "@/store.js";
+import { defaultStore } from '@/store.js';
 
 const excludeMutingUsers = ref(false);
 const excludeInactiveUsers = ref(false);
diff --git a/packages/frontend/src/pages/settings/migration.vue b/packages/frontend/src/pages/settings/migration.vue
index 15bf4691b2..d4c51a7c80 100644
--- a/packages/frontend/src/pages/settings/migration.vue
+++ b/packages/frontend/src/pages/settings/migration.vue
@@ -27,7 +27,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 		</div>
 	</MkFolder>
 
-	<MkFolder :defaultOpen="!!$i?.movedTo">
+	<MkFolder :defaultOpen="!!$i.movedTo">
 		<template #icon><i class="ti ti-plane-departure"></i></template>
 		<template #label>{{ i18n.ts._accountMigration.moveTo }}</template>
 
@@ -68,21 +68,23 @@ import MkUserInfo from '@/components/MkUserInfo.vue';
 import * as os from '@/os.js';
 import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { unisonReload } from '@/scripts/unison-reload.js';
 
+const $i = signinRequired();
+
 const moveToAccount = ref('');
 const movedTo = ref<Misskey.entities.UserDetailed>();
 const accountAliases = ref(['']);
 
 async function init() {
-	if ($i?.movedTo) {
+	if ($i.movedTo) {
 		movedTo.value = await os.api('users/show', { userId: $i.movedTo });
 	} else {
 		moveToAccount.value = '';
 	}
 
-	if ($i?.alsoKnownAs && $i.alsoKnownAs.length > 0) {
+	if ($i.alsoKnownAs && $i.alsoKnownAs.length > 0) {
 		const alsoKnownAs = await os.api('users/show', { userIds: $i.alsoKnownAs });
 		accountAliases.value = (alsoKnownAs && alsoKnownAs.length > 0) ? alsoKnownAs.map(user => `@${Misskey.acct.toString(user)}`) : [''];
 	} else {
diff --git a/packages/frontend/src/pages/settings/mute-block.instance-mute.vue b/packages/frontend/src/pages/settings/mute-block.instance-mute.vue
index 4b5080ea8f..8dc3e1acb4 100644
--- a/packages/frontend/src/pages/settings/mute-block.instance-mute.vue
+++ b/packages/frontend/src/pages/settings/mute-block.instance-mute.vue
@@ -20,10 +20,12 @@ import MkTextarea from '@/components/MkTextarea.vue';
 import MkInfo from '@/components/MkInfo.vue';
 import MkButton from '@/components/MkButton.vue';
 import * as os from '@/os.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { i18n } from '@/i18n.js';
 
-const instanceMutes = ref($i!.mutedInstances.join('\n'));
+const $i = signinRequired();
+
+const instanceMutes = ref($i.mutedInstances.join('\n'));
 const changed = ref(false);
 
 async function save() {
diff --git a/packages/frontend/src/pages/settings/mute-block.vue b/packages/frontend/src/pages/settings/mute-block.vue
index 83f7baf428..dfb72a87dd 100644
--- a/packages/frontend/src/pages/settings/mute-block.vue
+++ b/packages/frontend/src/pages/settings/mute-block.vue
@@ -9,14 +9,14 @@ SPDX-License-Identifier: AGPL-3.0-only
 		<template #icon><i class="ti ti-message-off"></i></template>
 		<template #label>{{ i18n.ts.wordMute }}</template>
 
-		<XWordMute :muted="$i!.mutedWords" @save="saveMutedWords"/>
+		<XWordMute :muted="$i.mutedWords" @save="saveMutedWords"/>
 	</MkFolder>
 
 	<MkFolder>
 		<template #icon><i class="ti ti-message-off"></i></template>
 		<template #label>{{ i18n.ts.hardWordMute }}</template>
 
-		<XWordMute :muted="$i!.hardMutedWords" @save="saveHardMutedWords"/>
+		<XWordMute :muted="$i.hardMutedWords" @save="saveHardMutedWords"/>
 	</MkFolder>
 
 	<MkFolder>
@@ -136,9 +136,11 @@ import { definePageMetadata } from '@/scripts/page-metadata.js';
 import MkUserCardMini from '@/components/MkUserCardMini.vue';
 import * as os from '@/os.js';
 import { infoImageUrl } from '@/instance.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import MkFolder from '@/components/MkFolder.vue';
 
+const $i = signinRequired();
+
 const renoteMutingPagination = {
 	endpoint: 'renote-mute/list' as const,
 	limit: 10,
diff --git a/packages/frontend/src/pages/settings/notifications.vue b/packages/frontend/src/pages/settings/notifications.vue
index 98b82f7116..1e9515e588 100644
--- a/packages/frontend/src/pages/settings/notifications.vue
+++ b/packages/frontend/src/pages/settings/notifications.vue
@@ -62,12 +62,14 @@ import FormSection from '@/components/form/section.vue';
 import MkFolder from '@/components/MkFolder.vue';
 import MkSwitch from '@/components/MkSwitch.vue';
 import * as os from '@/os.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import MkPushNotificationAllowButton from '@/components/MkPushNotificationAllowButton.vue';
 import { notificationTypes } from '@/const.js';
 
+const $i = signinRequired();
+
 const nonConfigurableNotificationTypes = ['note', 'roleAssigned', 'followRequestAccepted', 'achievementEarned'];
 
 const allowButton = shallowRef<InstanceType<typeof MkPushNotificationAllowButton>>();
@@ -86,11 +88,11 @@ async function readAllNotifications() {
 async function updateReceiveConfig(type, value) {
 	await os.apiWithDialog('i/update', {
 		notificationRecieveConfig: {
-			...$i!.notificationRecieveConfig,
+			...$i.notificationRecieveConfig,
 			[type]: value,
 		},
 	}).then(i => {
-		$i!.notificationRecieveConfig = i.notificationRecieveConfig;
+		$i.notificationRecieveConfig = i.notificationRecieveConfig;
 	});
 }
 
diff --git a/packages/frontend/src/pages/settings/other.vue b/packages/frontend/src/pages/settings/other.vue
index 340a9550b4..f6f0b8daa4 100644
--- a/packages/frontend/src/pages/settings/other.vue
+++ b/packages/frontend/src/pages/settings/other.vue
@@ -94,25 +94,19 @@ import MkKeyValue from '@/components/MkKeyValue.vue';
 import MkButton from '@/components/MkButton.vue';
 import * as os from '@/os.js';
 import { defaultStore } from '@/store.js';
-import { signout, $i } from '@/account.js';
+import { signout, signinRequired } from '@/account.js';
 import { i18n } from '@/i18n.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import { unisonReload } from '@/scripts/unison-reload.js';
 import FormSection from '@/components/form/section.vue';
 
+const $i = signinRequired();
+
 const reportError = computed(defaultStore.makeGetterSetter('reportError'));
 const enableCondensedLineForAcct = computed(defaultStore.makeGetterSetter('enableCondensedLineForAcct'));
 const devMode = computed(defaultStore.makeGetterSetter('devMode'));
 const defaultWithReplies = computed(defaultStore.makeGetterSetter('defaultWithReplies'));
 
-function onChangeInjectFeaturedNote(v) {
-	os.api('i/update', {
-		injectFeaturedNote: v,
-	}).then((i) => {
-		$i!.injectFeaturedNote = i.injectFeaturedNote;
-	});
-}
-
 async function deleteAccount() {
 	{
 		const { canceled } = await os.confirm({
diff --git a/packages/frontend/src/pages/settings/privacy.vue b/packages/frontend/src/pages/settings/privacy.vue
index 67a2f2cb40..4f5bc847ac 100644
--- a/packages/frontend/src/pages/settings/privacy.vue
+++ b/packages/frontend/src/pages/settings/privacy.vue
@@ -80,9 +80,11 @@ import MkFolder from '@/components/MkFolder.vue';
 import * as os from '@/os.js';
 import { defaultStore } from '@/store.js';
 import { i18n } from '@/i18n.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 
+const $i = signinRequired();
+
 const isLocked = ref($i.isLocked);
 const autoAcceptFollowed = ref($i.autoAcceptFollowed);
 const noCrawle = ref($i.noCrawle);
@@ -90,8 +92,8 @@ const preventAiLearning = ref($i.preventAiLearning);
 const isExplorable = ref($i.isExplorable);
 const hideOnlineStatus = ref($i.hideOnlineStatus);
 const publicReactions = ref($i.publicReactions);
-const followingVisibility = ref($i?.followingVisibility);
-const followersVisibility = ref($i?.followersVisibility);
+const followingVisibility = ref($i.followingVisibility);
+const followersVisibility = ref($i.followersVisibility);
 
 const defaultNoteVisibility = computed(defaultStore.makeGetterSetter('defaultNoteVisibility'));
 const defaultNoteLocalOnly = computed(defaultStore.makeGetterSetter('defaultNoteLocalOnly'));
diff --git a/packages/frontend/src/pages/settings/profile.vue b/packages/frontend/src/pages/settings/profile.vue
index d28c8284cf..57d84b9619 100644
--- a/packages/frontend/src/pages/settings/profile.vue
+++ b/packages/frontend/src/pages/settings/profile.vue
@@ -120,7 +120,7 @@ import FormSlot from '@/components/form/slot.vue';
 import { selectFile } from '@/scripts/select-file.js';
 import * as os from '@/os.js';
 import { i18n } from '@/i18n.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { langmap } from '@/scripts/langmap.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import { claimAchievement } from '@/scripts/achievements.js';
@@ -128,6 +128,8 @@ import { defaultStore } from '@/store.js';
 import MkInfo from '@/components/MkInfo.vue';
 import MkTextarea from '@/components/MkTextarea.vue';
 
+const $i = signinRequired();
+
 const Sortable = defineAsyncComponent(() => import('vuedraggable').then(x => x.default));
 
 const reactionAcceptance = computed(defaultStore.makeGetterSetter('reactionAcceptance'));
@@ -148,7 +150,7 @@ watch(() => profile, () => {
 	deep: true,
 });
 
-const fields = ref($i?.fields.map(field => ({ id: Math.random().toString(), name: field.name, value: field.value })) ?? []);
+const fields = ref($i.fields.map(field => ({ id: Math.random().toString(), name: field.name, value: field.value })) ?? []);
 const fieldEditMode = ref(false);
 
 function addField() {
diff --git a/packages/frontend/src/pages/settings/roles.vue b/packages/frontend/src/pages/settings/roles.vue
index 40671f7132..bb37730e35 100644
--- a/packages/frontend/src/pages/settings/roles.vue
+++ b/packages/frontend/src/pages/settings/roles.vue
@@ -27,15 +27,11 @@ import { computed } from 'vue';
 import FormSection from '@/components/form/section.vue';
 import * as os from '@/os.js';
 import { i18n } from '@/i18n.js';
-import { $i } from '@/account.js';
+import { signinRequired } from '@/account.js';
 import { definePageMetadata } from '@/scripts/page-metadata.js';
 import MkRolePreview from '@/components/MkRolePreview.vue';
 
-function save() {
-	os.apiWithDialog('i/update', {
-
-	});
-}
+const $i = signinRequired();
 
 const headerActions = computed(() => []);