Merge pull request #3614 from wangeditor-team/fix-head-set-up

fix: 修复设置标题控制台报错的bug

Author: wangfupeng1988

src/menus/head/index.ts

@@ -33,6 +33,9 @@ class Head extends DropListMenu implements MenuActive {
                 },
             ],
             clickHandler: (value: string) => {
+                if (editor.$textElem.html() === EMPTY_P) {
+                    return
+                }
                 // 注意 this 是指向当前的 Head 对象
                 this.command(value)
             },