Potential breaking change in upcoming Svelte version

[rmunn]

In sveltejs/svelte#6750, there is a proposed change to the StartStopNotifier type of Svelte stores, which will be a breaking change for anyone creating custom stores. See the PR for details, but the short version is that if that PR is accepted and merged into Svelte, you'll need to make some small changes to your custom store to maintain Svelte compatibility, as follows:

1. Inside your writable function, change stop = start(set) || noop; to stop = start(set, update) || noop; in the subscribe() implementation.
2. Inside your derived function, change return readable(initial_value, (set) => { to return readable(initial_value, (set, update) => { and then change const result = fn(single ? values[0] : values, set); to const result = fn(single ? values[0] : values, set, update);

In your repo, the affected code appears to be in store.js.

If you have any comments about the proposed breaking change, please come leave a comment on the Svelte PR to let me know whether it would make your life easier or harder.