SIGX401 · Topic created on a destroyed group#

Dev message

[sigx] Cannot create topic "user:updated" on a destroyed topic group.

Suggestion

The group was destroyed; create its topics before destroy(), or recreate the group.

What happened#

A topic group was asked for a topic after its destroy() had run.

A group owns its topics: destroying it destroys all of them, and it stops handing out new ones. Any topic it created now would be born with no path to a subscriber, so SignalX throws at the call site rather than returning a dead object.

Like SIGX400, this is a teardown-ordering problem — something is still reaching for the group after the code that owns it has torn it down. Usually:

  • A late async callback creates its topic after teardown.
  • A component asks the group for a topic while an ancestor is unmounting.
  • A group is stored at module scope and destroyed on hot reload, while live code still holds it.

Fix it#

Create the group's topics while it's alive, and don't reach for it after teardown:

TypeScript 
const group = createTopicGroup();
const updated = group.topic<User>('user:updated');

// … later, on teardown:
group.destroy();   // `updated` is destroyed too

If a new lifecycle begins, create a new group rather than reusing the destroyed one:

TypeScript 
let group = createTopicGroup();

function restart() {
    group.destroy();
    group = createTopicGroup();   // fresh group, fresh topics
}