Fix Editor Reactivity

[nVitius]

When using the useEditor composable, the Ref that is returned observes changes on the Editor's own properties, causing any effects that reference editor to trigger unnecessarily.

Even though the Editor's constructor uses markRaw, using ref wraps your value in an object and makes it reactive internally. You can see this happening here: https://github.com/vuejs/composition-api/blob/main/src/reactivity/ref.ts#L82
The check for isRaw only happens on the parent, which in this case is the wrapper object.

Using shallowRef instead allows us to create effects that trigger when the Editor is instantiated (in the onMounted) while preventing reactivity of the Editor's properties. From the Vue docs:

Creates a ref that tracks its own .value mutation but doesn't make its value reactive.

[philippkuehn]

great! thanks for the explanation!