[kaan650]

When a component returned with a delay is destroyed and one of its cleanups errors, the timeout callback in switch(), indexes() and values() stops before removing the scope and updating the output. The timeout doesn't run again, so the destroyed component stays in the output for good.

local key = source "a"

local output = switch(key) {
    a = function()
        cleanup(function() error("oops") end)
        return create "Frame" {}, 0.5
    end,
    b = function() return create "Frame" {} end,
}

key "b"
-- 0.5 seconds later the cleanup errors and output() still has both frames

This removes the scope and updates the output before rethrowing the error.