Avoid double-destroying instances

[Meta-Maxim]

May be another solution here, but my janitors run into errors when used in the following configuration:

1. GuiModule creates a gui, adds to guiJanitor
2. GuiModule creates a GuiComponent class, which uses LinkToInstance to destroy the component when the component's gui is destroyed.
3. Gui class calls guiJanitor:Cleanup(), destroying the gui and the descendant component instance. This triggers the component class's LinkToInstance cleanup after the descendant component instance was already destroyed, resulting in an error.

As it's impossible to check if an instance has been destroyed already as opposed to just parented to nil, this change adds a pcall for only instance:Destroy() calls during cleanup.

Simple case:

local j = Janitor.new()
j:Add(workspace.p)
j:LinkToInstance(workspace.p)
workspace.p:Destroy() -- Ancestor destroyed maybe
--> `The Parent property of Workspace.p is locked`

[howmanysmall]

i actually almost added this for 1.15

[howmanysmall]

what i was thinking of doing is instead of this, making it a toggle option like i originally intended

[Meta-Maxim]

If you mean the component janitor can mark that instances may be destroyed for other reasons/errorOnCleaningDestroyed then that sounds better, the double-destruction error could be a useful for other designs

[Meta-Maxim]

@howmanysmall Added a toggle .SuppressInstanceReDestroy = false -- default

[howmanysmall]

You're gonna need to pull from the latest if you want this merged.

[Meta-Maxim]

✅

[howmanysmall]

Okay, sorry about the delay. Pull again and I'll finally merge.

[howmanysmall]

There you go.