Svelte: Svelte update (3.5.1 > 3.5.2) and BOOOM! (problems, not joys)

[frederikhors]

Taking https://codesandbox.io/s/reverent-tesla-c0kq0 from https://github.com/lukeed/navaid/issues/13.

FIRST PROBLEM

I cannot navigate anymore.

Until 3.5.1 you can navigate like this:

1. Being in Home ("/")
2. click on "Go to Teams Page" ("/teams")
3. click on "Go to Team 1 Page" ("team/1")

With 3.5.2 you can't.

You can do 1 and 2 but at the step 3 you see nothing.

If you are on the page "team/1" and reload using codesandbox's preview icon it works.

SECOND PROBLEM

In one of my projects the error is even more frightening:

TypeError: Cannot read property '$$' of undefined

[frederikhors]

Maybe related: https://github.com/sveltejs/svelte/issues/3055

[lukeed]

The problem _is_ the "second problem" – that runtime error appears, killing the route/display.

The error appears in two forms:

function flush() {
    const seen_callbacks = new Set();
    do {
        // first, call beforeUpdate functions
        // and update components
        while (dirty_components.length) {
            const component = dirty_components.shift();
            set_current_component(component);
            update(component.$$); //<~ here
        }
        // ...
}

And here:

i: function intro(local) {
      if (current) return;
      (0, _internal.transition_in)(switch_instance.$$.fragment, local);
      current = true;
    },

They both seem to stem from a transition_in

function transition_in(block, local) {
    if (block && block.i) {
        outroing.delete(block);
        block.i(local);
    }
}

[Conduitry]

Can you try with v3.5.3?

[Rich-Harris]

I just tried it — still broken

[Rich-Harris]

Am I right in thinking this was Navaid-related, and is fixed with Navaid 1.0.5?

[lukeed]

Nope 😬 still happens with latest versions of each

[Rich-Harris]

Simpler repro: https://svelte.dev/repl/834b039bc5c74e7dbbf8efa2ac10651b?version=3.5.4

[Rich-Harris]

Fixed in 3.6.0! thanks

[frederikhors]

Fixed in 3.6.0! thanks

Thanks only to you actually.