{:then} / {:catch} require whitespace but not an identifier for resolution/rejection value

[Conduitry]

Using {:then} or {:catch} throws an error compiling, saying there is whitespace expected (after the then/catch). If whitespace is added, {:then } and {:catch } are accepted, and afaict things work fine with no identifier to store the resolution or rejection value in.

I'm not 100% clear on whether we want to allow identifier-less {:then} and {:catch} blocks (probably? It's not in the docs but I don't see the harm), but if so, we shouldn't be requiring whitespace.

[kaisermann]

I'm making a dialog component that closes after a certain promise is resolved and changes its content based on the promise state. In this case, the resolved/rejected data is irrelevant:

<AsyncDialog {promise} duration={3000}>
  {#await promise}
    <span>Loading...</span>
  {:then}
    <span>Success!</span>
  {:catch}
    <span>Error :(</span>
  {/await}
</AsyncDialog>

[Rich-Harris]

Released 2.9.4 with the fix — thanks