インデクサーを忘れていた

src/client/app/desktop/views/components/post-form.vue

@@ -186,7 +186,7 @@ export default Vue.extend({
 			this.$nextTick(() => this.watch());
 
 			const hashtags = [...document.getElementsByClassName('hashtag')];
-			const hashtagsContainer = hashtags.parentElement;
+			const hashtagsContainer = hashtags[0].parentElement;
 			let offsetX = 0
 			const update = () => {
 				if (hashtags[0].getBoundingClientRect().right <= hashtagsContainer.getBoundingClientRect().left) {