Error thrown when using custom defered transition as a bidirectional transition

[oskar-koli]

Describe the bug

Using a defered bidirectional transition throws an error:

Uncaught (in promise) TypeError: outros is undefined
    go chunk-K6MJRMI7.js?v=2acd031f:1227
    run chunk-K6MJRMI7.js?v=2acd031f:1278

It works fine if implemented as a non-defered transition.

The code from the repro case below:

<script lang="ts">
  function customTransition() {
    return () => {
      return {
        duration: 2000
      }
    }
  }
</script>

<button on:click transition:customTransition>
  <slot></slot>
</button>

Reproduction

Stackbliz example here.

To reproduce, click on the button and the error is thrown.

Logs

Uncaught (in promise) TypeError: outros is undefined
    go chunk-K6MJRMI7.js?v=2acd031f:1227
    run chunk-K6MJRMI7.js?v=2acd031f:1278
    promise chunk-K6MJRMI7.js?v=2acd031f:1276
    outro /src/lib/Counter.svelte:89
    transition_out chunk-K6MJRMI7.js?v=2acd031f:1073
    outro /src/App.svelte:68
    transition_out chunk-K6MJRMI7.js?v=2acd031f:1073
    update /src/App.svelte:327
    update chunk-K6MJRMI7.js?v=2acd031f:1021
    flush chunk-K6MJRMI7.js?v=2acd031f:987

System Info

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: 16.14.2 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 7.17.0 - /usr/local/bin/npm
  npmPackages:
    svelte: ^3.55.1 => 3.55.1

Severity

annoyance