Incorrect widget ZIndex when using widgets inside conditional blocks

[MrBlackbrow]

Overview

I noticed that having a widget in a conditional block causes it to have the same widget ZIndex as the first widget after the conditional block.

It seems like a non-trivial issue to solve, so I'd also appreciate any workarounds.

Reproduction steps

1. Run this code with Iris

local err = Iris.State(nil)
if Iris.Button("Cause error").clicked() then
    err:set("An error has occurred!")
end

if err:get() then
    Iris.Text(err:get())
end

Iris.Text("Some text afterwards")

2. Press the button
3. Observe this result