`TypeError: Cannot read properties of undefined (reading 'default')` after upgrading to `2.2.0`

[Saibamen]

at Router.svelte:45:28

Line 45: if (default_slot) default_slot.c();

This runtime error was introduced in svelte-routing 2.2.0.

Version 2.1.0 is OK.

Related: https://github.com/EmilTholin/svelte-routing/pull/258

[krishnaTORQUE]

svelte version: ?? svelte-routing version: ??

[Saibamen]

svelte: 4.2.2 svelte-routing 2.2.0

[krishnaTORQUE]

Can you please try latest version of svelte-routing?

[Saibamen]

This same bug in 2.5.0

[krishnaTORQUE]

@motzel Could you please have look, Thanks

[motzel]

This line in the source code is completely different. The only places where the default property is read are:

https://github.com/EmilTholin/svelte-routing/blob/2673fe7c5a76d079a879f3f3a8dd03db9183b2f3/src/Router.svelte#L52 https://github.com/EmilTholin/svelte-routing/blob/2673fe7c5a76d079a879f3f3a8dd03db9183b2f3/src/utils.js#L33 https://github.com/EmilTholin/svelte-routing/blob/2673fe7c5a76d079a879f3f3a8dd03db9183b2f3/src/utils.js#L100

and none of them were changed in my PR. My guess is that the problem is in either of the last two, because the pick() function is used in Router.svelte. But I'm not able to reproduce it, it works for me.

@Saibamen Could you prepare a minimal example in which this bug appears? Or just replace route.default in these two lines in utils.js with route?.default and please check if it works.

[Saibamen]

Full stacktrace (version 2.2.0):

Uncaught TypeError: Cannot read properties of undefined (reading 'default')
    at Router.svelte:45:28
    at sync (index.js:150:19)
    at index.js:173:3
    at Object.subscribe2 [as subscribe] (index.js:82:11)
    at subscribe (utils.js:139:22)
    at component_subscribe (utils.js:159:31)
    at instance3 (Router.svelte:34:28)
    at init (Component.js:135:5)
    at new Router (Router.svelte:96:54)
    at create_fragment (Navigation.svelte:17:15)

[Saibamen]

@motzel: I added ? to utils.js and Router.svelte and nothing was changed. Error and stack trace is the same

[motzel]

@Saibamen This is all the way impossible, because there is no other reading of default property in the whole svelte-routing code. And even more so in line 45 of Router.svelte, because there is something else there. Could you please show the full stacktrace with the error? Although some minimal example of where the error occurs would be best.

[motzel]

Oh, I didn't notice that you already added the full stacktrace (I'm on mobile now), sorry

[motzel]

@Saibamen I have prepared a minimal example of svelte-routing (based on the documentation from the readme). It uses svelte-routing@2.2.0 and svelte@4.2.2, just like your project. Could you fork it and break it in the same way as in your project?

https://github.com/motzel/svelte-routing-example

[Saibamen]

@motzel: Working version: https://github.com/Saibamen/svelte-routing-example/tree/2-1-0_working

Upgrade svelte-routing to version 2.2.0 and it will have this exception.

[motzel]

Thanks! I'll check it out today after work (~in 8h)