SSAOPass.dispose() broken

[drcmda]

Description of the problem

We noticed this first here: https://codesandbox.io/s/react-three-fiber-blob-qv9ww?from-embed

Go anywhere in the code and make a new line by hitting enter, it compiles then crashes (in the browser console). This happens because components unmount and dispose is called on the effect.

Plain JS example:

import * as THREE from 'three'
import { SSAOPass } from 'three/examples/jsm/postprocessing/SSAOPass'

const s = new THREE.Scene()
const c = new THREE.Camera()
const q = new SSAOPass(s,c)
q.dispose() // crash

SSAOPass tries to dispose some quad, but that quad is neither part of SSAOPass, nor Pass, looks to me like a leftover.

this.quad.geometry.dispose(); // dispose materials

SSAOPass.js:138 Uncaught TypeError: Cannot read property 'geometry' of undefined
    at SSAOPass.dispose (SSAOPass.js:138)

I thought about making a PR but wasn't sure, maybe this quad does belong in there and comes from somewhere else?

[Mugen87]

You can just remove the line for now.

We should consider to enhance Pass.FullScreenQuad with a dispose() method. But this can be done in a later PR.

[drcmda]

great! it's done.