fix(vitepress-twoslash): empty twoslash error at end of the line (#999)

Co-authored-by: Anthony Fu <github@antfu.me>

Author: zzxming

packages/vitepress-twoslash/src/renderer-floating-vue.ts

@@ -173,6 +173,11 @@ function renderMarkdownInline(this: ShikiTransformerContextCommon, md: string, c
 }
 
 function compose(parts: { token: Element | Text, popup: Element }): Element[] {
+  if (parts.token.type === 'element' && parts.token.children.length < 1) {
+    const classes = parts.token.properties.class || ''
+    parts.token.properties.class = `${classes} twoslash-error-empty`
+  }
+
   return [
     {
       type: 'element',

packages/vitepress-twoslash/src/style.css

@@ -141,3 +141,11 @@
 .twoslash-floating.twoslash-completion .twoslash-completion-list li {
   padding: 3px 0;
 }
+
+.twoslash-error:empty,
+.twoslash-error-empty {
+  display: inline-block;
+  min-width: 0.55em;
+  min-height: 1.2em;
+  vertical-align: middle;
+}