vr-mode-ui component can't be reenabled after being disabled

Description:

• A-Frame Version: 0.9.0
• Platform / Device: Chrome on desktop
• Reproducible Code Snippet or URL: https://aframe.io/aframe/examples/boilerplate/hello-world/

Open the console:

AFRAME.scenes[0].setAttribute('vr-mode-ui', {enabled: false});
undefined
AFRAME.scenes[0].setAttribute('vr-mode-ui', {enabled: true});
component.js:681 Uncaught TypeError: Cannot set property 'enabled' of undefined
    at extendProperties (component.js:681)
    at i.callUpdateHandler (component.js:393)
    at i.updateProperties (component.js:277)
    at HTMLElement.value (a-entity.js:478)
    at HTMLElement.value (a-scene.js:648)
    at HTMLElement.<anonymous> (a-entity.js:715)
    at HTMLElement.value (a-scene.js:487)
    at <anonymous>:1:18

The first time, in vr-mode-ui update function, it calls this.remove(); which executes wrapRemove (in src/core/component.js) with the line this.attrValue = this.oldData = this.parsingAttrValue = undefined;

The second call will call (in src/core/component.js) extendProperties(dest, source, isObjectBased) with dest undefined (this.oldData)

The wrapRemove stuff was introduced in aframe 0.9.0 with the object pool.

[vincentfretin]

I reopened. The issue exists since 0.7.0 or before. Setting enabled: false and later setting to enabled: true does not show up again the button.

[Utopiah]

As the behaviour is not predictable could be reflected in the documentation.