SSR not showing any warning for unknown tag

[IlyaSemenov]

Version

2.5.3

Reproduction link

https://jsfiddle.net/semenov/1oa635w8/

Steps to reproduce

Run jsfiddle and note the warning message that is printed to the console.

Then run the same code with SSR:

const Vue = require('vue')
const app = new Vue({
  template: '<div><bing-bang/></div>',
})

const renderer = require('vue-server-renderer').createRenderer()

renderer.renderToString(app, (err, html) => {
  if (err) throw err
  console.log(html)
})

Like this: DEBUG=* node test.js

What is expected?

The SSR rendering prints a warning similar to what client-side rendering emits:

[Vue warn]: Unknown custom element: <bing-bang> - did you register the component correctly? For recursive components, make sure to provide the "name" option.

(found in <Root>)

What is actually happening?

SSR simply renders invalid HTML:

<div data-server-rendered="true"><bing-bang></bing-bang></div>

without any warnings.

---

This inconsistency makes it hard to refactor big Nuxt.js apps, as missing/unregistered components get silently ignored.

[LinusBorg]

Doesn't the warning appear on the client anyway?

[IlyaSemenov]

No, at least not on the initial SSR-generated page load (with Nuxt). It only shows a warning on the client when you arrive at the page with <nuxt-link>.

But this is actually a valid point... I would also expect the client to emit that error on the initial load of such SSR-generated page.

[yyx990803]

FYI It is expected behavior to not warn on the server, because it's possible that the user wants to render a real custom element instead of a Vue component. The warning can only be safely performed on the client where we can check if the element is registered as a real custom element.

Previously it is not warning even on client-side hydration, which is fixed in df82aeb.