diff --git a/packages/frontend/src/pages/chat/XMessage.vue b/packages/frontend/src/pages/chat/XMessage.vue
index b1be8d5fd4..3eb2ae8092 100644
--- a/packages/frontend/src/pages/chat/XMessage.vue
+++ b/packages/frontend/src/pages/chat/XMessage.vue
@@ -25,8 +25,8 @@ SPDX-License-Identifier: AGPL-3.0-only
 		<div :class="$style.footer">
 			<button class="_textButton" style="color: currentColor;" @click="showMenu"><i class="ti ti-dots-circle-horizontal"></i></button>
 			<MkTime :class="$style.time" :time="message.createdAt"/>
-			<MkA v-if="isSearchResult && 'toRoom' in message && message.toRoom != null" :to="`/chat/room/${message.toRoomId}`">{{ message.toRoom?.name }}</MkA>
-			<MkA v-if="isSearchResult && 'toUser' in message && message.toUser != null && isMe" :to="`/chat/user/${message.toUserId}`">@{{ message.toUser?.username }}</MkA>
+			<MkA v-if="isSearchResult && 'toRoom' in message && message.toRoom != null" :to="`/chat/room/${message.toRoomId}`">{{ message.toRoom.name }}</MkA>
+			<MkA v-if="isSearchResult && 'toUser' in message && message.toUser != null && isMe" :to="`/chat/user/${message.toUserId}`">@{{ message.toUser.username }}</MkA>
 		</div>
 		<TransitionGroup
 			:enterActiveClass="prefer.s.animation ? $style.transition_reaction_enterActive : ''"
@@ -36,7 +36,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 			:moveClass="prefer.s.animation ? $style.transition_reaction_move : ''"
 			tag="div" :class="$style.reactions"
 		>
-			<div v-for="record in message.reactions" :key="record.reaction + record.user?.id" :class="[$style.reaction, record.user?.id === $i.id ? $style.reactionMy : null]" @click="onReactionClick(record)">
+			<div v-for="record in message.reactions" :key="record.reaction + record.user.id" :class="[$style.reaction, record.user.id === $i.id ? $style.reactionMy : null]" @click="onReactionClick(record)">
 				<MkAvatar :user="record.user!" :link="false" :class="$style.reactionAvatar"/>
 				<MkReactionIcon
 					:withTooltip="true"
@@ -111,13 +111,13 @@ function react(ev: MouseEvent) {
 function onReactionClick(record: Misskey.entities.ChatMessage['reactions'][0]) {
 	if (!$i.policies.canChat) return;
 
-	if (record.user?.id === $i.id) {
+	if (record.user.id === $i.id) {
 		misskeyApi('chat/messages/unreact', {
 			messageId: props.message.id,
 			reaction: record.reaction,
 		});
 	} else {
-		if (!props.message.reactions.some(r => r.user?.id === $i.id && r.reaction === record.reaction)) {
+		if (!props.message.reactions.some(r => r.user.id === $i.id && r.reaction === record.reaction)) {
 			sound.playMisskeySfx('reaction');
 			misskeyApi('chat/messages/react', {
 				messageId: props.message.id,
diff --git a/packages/frontend/src/pages/chat/room.members.vue b/packages/frontend/src/pages/chat/room.members.vue
index 80e387d179..5a574068cb 100644
--- a/packages/frontend/src/pages/chat/room.members.vue
+++ b/packages/frontend/src/pages/chat/room.members.vue
@@ -14,8 +14,8 @@ SPDX-License-Identifier: AGPL-3.0-only
 	<hr v-if="memberships.length > 0">
 
 	<div v-for="membership in memberships" :key="membership.id" :class="$style.membership">
-		<MkA v-if="membership.user != null" :class="$style.membershipBody" :to="`${userPage(membership.user)}`">
-			<MkUserCardMini :user="membership.user"/>
+		<MkA :class="$style.membershipBody" :to="`${userPage(membership.user!)}`">
+			<MkUserCardMini :user="membership.user!"/>
 		</MkA>
 	</div>
 
diff --git a/packages/frontend/src/pages/chat/room.vue b/packages/frontend/src/pages/chat/room.vue
index 4932ac722d..664f421c5c 100644
--- a/packages/frontend/src/pages/chat/room.vue
+++ b/packages/frontend/src/pages/chat/room.vue
@@ -178,10 +178,10 @@ async function initialize() {
 		connection.value = useStream().useChannel('chatUser', {
 			otherId: user.value.id,
 		});
-		connection.value?.on('message', onMessage);
-		connection.value?.on('deleted', onDeleted);
-		connection.value?.on('react', onReact);
-		connection.value?.on('unreact', onUnreact);
+		connection.value.on('message', onMessage);
+		connection.value.on('deleted', onDeleted);
+		connection.value.on('react', onReact);
+		connection.value.on('unreact', onUnreact);
 	} else {
 		const [r, m] = await Promise.all([
 			misskeyApi('chat/rooms/show', { roomId: props.roomId }),
@@ -272,10 +272,10 @@ function onReact(ctx: Parameters<Misskey.Channels['chatUser']['events']['react']
 				reaction: ctx.reaction,
 				user: message.fromUserId === $i.id ? user.value! : $i,
 			});
-		} else if (ctx.user != null) {
+		} else {
 			message.reactions.push({
 				reaction: ctx.reaction,
-				user: ctx.user,
+				user: ctx.user!,
 			});
 		}
 	}
@@ -283,7 +283,7 @@ function onReact(ctx: Parameters<Misskey.Channels['chatUser']['events']['react']
 
 function onUnreact(ctx: Parameters<Misskey.Channels['chatUser']['events']['unreact']>[0] | Parameters<Misskey.Channels['chatRoom']['events']['unreact']>[0]) {
 	const message = messages.value.find(m => m.id === ctx.messageId);
-	if (message && ctx.user != null) {
+	if (message) {
 		const index = message.reactions.findIndex(r => r.reaction === ctx.reaction && r.user.id === ctx.user!.id);
 		if (index !== -1) {
 			message.reactions.splice(index, 1);
@@ -318,12 +318,14 @@ async function inviteUser() {
 
 	const invitee = await os.selectUser({ includeSelf: false, localOnly: true });
 	os.apiWithDialog('chat/rooms/invitations/create', {
-		roomId: room.value?.id,
+		roomId: room.value.id,
 		userId: invitee.id,
 	});
 }
 
 async function leaveRoom() {
+	if (room.value == null) return;
+
 	const { canceled } = await os.confirm({
 		type: 'warning',
 		text: i18n.ts.areYouSure,
@@ -331,7 +333,7 @@ async function leaveRoom() {
 	if (canceled) return;
 
 	misskeyApi('chat/rooms/leave', {
-		roomId: room.value?.id,
+		roomId: room.value.id,
 	});
 	router.push('/chat');
 }