Transition regression since v5.38.2

[huntabyte]

Describe the bug

Starting in 5.38.2, exit transitions are no longer being applied under certain conditions while enter transitions are working as expected.

Reproduction below.

Reproduction

The following StackBlitz repro is pinned to 5.38.1, if you open and close the popover, you'll notice the enter and exit transitions are applied as expected.

If you bump the Svelte version to 5.38.2, you'll notice the transition is only applied during entrance, but not exit.

https://stackblitz.com/edit/jfqc8mm3?file=package.json

Logs

System Info

(StackBlitz env)
  System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 20.19.1 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    svelte: 5.38.2 => 5.38.2

Severity

blocking an upgrade

[hmnd]

@huntabyte this is fixed in #16930

See this patched repl :) (the pkg.new preview hasn't updated with my latest changes yet)