refactor: use ??

packages/client/src/components/MkPostForm.vue

@@ -556,7 +556,7 @@ function saveDraft() {
 }
 
 function deleteDraft() {
-	const draftData = JSON.parse(localStorage.getItem('drafts') || '{}');
+	const draftData = JSON.parse(localStorage.getItem('drafts') ?? '{}');
 
 	delete draftData[draftKey];
 
@@ -571,7 +571,7 @@ async function post() {
 		renoteId: props.renote ? props.renote.id : quoteId ? quoteId : undefined,
 		channelId: props.channel ? props.channel.id : undefined,
 		poll: poll,
-		cw: useCw ? cw || '' : undefined,
+		cw: useCw ? cw ?? '' : undefined,
 		localOnly: localOnly,
 		visibility: visibility,
 		visibleUserIds: visibility === 'specified' ? visibleUsers.map(u => u.id) : undefined,