Version

3.0.2

Reproduction link

https://codesandbox.io/s/elegant-chatterjee-7xfqw?file=/src/components/Tabs.vue

Steps to reproduce

Select the Bar tab in the reproduction example.

What is expected?

Display the activated slot.

What is actually happening?

Failure with error...

Cannot read property 'type' of undefined
    at patchBlockChildren (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3615:34
    at processFragment (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3656:9
    at patch (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3391:9
    at patchBlockChildren (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3616:7
    at patchElement (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3597:7
    at processElement (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3464:7
    at patch (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3395:11
    at componentEffect (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:3815:9
    at reactiveEffect (https://7xfqw.csb.app/node_modules/
vue/reactivity/dist/reactivity.esm-bundler.js:235:16
    at callWithErrorHandling (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:780:32
    at flushJobs (https://7xfqw.csb.app/node_modules/
vue/runtime-core/dist/runtime-core.esm-bundler.js:957:9

This tab component used to work, but is broken now. Any help would be greatly appreciated..

Your Tabs component is empty. If you provide a boiled down repro we can take a look

Remember to use the forum or the Discord chat to ask questions!

sorry @posva I've updated with a working link. although, it seems you must refresh the example once for it to display.