[Bug Report] el-cascader can not be precisely selected, and online testing is also problematic.

[hhch]

Element UI version

2.4.6

OS/Browsers version

chrome

Vue version

2.5.17

Reproduction Link

https://jsfiddle.net/26ungd0L/1/

Steps to reproduce

首先设置cascader为 expand-trigger="hover" :change-on-select="true"，然后随意将某一2级选项的children去掉，就是在官网的测试例子上把任意一个2级选项的子菜单去掉，然后开始测试，点击尝试选择该没有子元素的选项

What is Expected?

预期是该没有子菜单的选项能选中

What is actually happening?

结果是该没有子菜单的选项选不中，选到其他的选项了,因为单击选择的时候，面板上移隐藏，因为hover选择，选中其他选项了

点击Form，但是选中的却是其他选项

[element-bot]

Translation of this issue:

Element UI version
2.4.6

OS/Browsers version
Chrome

Vue version
2.5.17

Reproduction Link
https://jsfiddle.net/26ungd0L/1/

Steps to reproduce
Set the cascader to expand-trigger= "hover": change-on-select= "true" and then remove the child of a certain level 2 option at will, removing the submenu of any level 2 option from the test example on the official website, then start the test and click try to select the option that has no sub-elements.

What is Expected?
It is expected that the option with no submenus can be selected.

What is actually happening?
The result is that no submenu options are selected, and other options are selected.

[ziyoung]

Duplicate of #12508

[ziyoung]

升级一下版本，这个问题已经修复了。