The setCurrentKey method of the [Bug Report] tree component cannot cancel node highlighting

[zywu2]

Element UI version

2.9.1

OS/Browsers version

macOS 10.13.6 / Google Chrome 74.0.3729.169

Vue version

2.6.10

Reproduction Link

https://codepen.io/zywu2/pen/zVKeOa?editors=1111

Steps to reproduce

setCurrentKey不传参数时，无法取消当前选中节点

What is Expected?

setCurrentKey不传参数时，可以取消当前选中节点

What is actually happening?

setCurrentKey不传参数时，无法取消当前选中节点

[element-bot]

Translation of this issue:

Element UI version

2.9.1

OS/Browsers version

MacOS 10.13.6 / Google Chrome 74.0.3729.169

Vue version

2.6.10

Reproduction Link

Https://codepen.io/zywu2/pen/zVKeOa?Editors=1111

Steps to reproduce

When setCurrentKey does not pass parameters, the currently selected node cannot be cancelled

What is Expected?

When setCurrentKey does not pass parameters, you can cancel the currently selected node

What is actually happening?

When setCurrentKey does not pass parameters, the currently selected node cannot be cancelled