TypeError when route-link with sibling slot used

[Darkside73]

Vue.js version

2.1.7

Reproduction Link

https://jsfiddle.net/1anum7y4/1/

This template fails to compile if no default slot given

<p>
  <router-link :to="{ name: 'foo' }">foo</router-link>
  <slot></slot>
</p>

It does not reproduce if slot given or <slot></slot> wrapped by any tag

What is Expected?

Component renders without slot

What is actually happening?

Uncaught TypeError: Cannot set property 'isRootInsert' of undefined

[mochetts]

Having same issue in a SPA...

Downgraded to 2.1.6 and there it seems to work fine.

[johnleider]

Same, submitted issue on the vue-router repo #1051.

[samuelantonioli]

the problem

The difference seems to be the following between the versions:
Vue 2.1.7 calls createElm with an undefined vnode (createElm(undefined, ...))

console.log in createElm reveals the following:

Vue 2.1.6:

Vue 2.1.7:

So the problem is that createElem gets called with an undefined vnode.
calling Vue 2.1.6's createElm with an undefined vnode creates the same error:

Uncaught TypeError: Cannot set property 'isRootInsert' of undefined

---

bug

The relevant part is here: src/core/vdom/patch.js#L89

---

solution

I think it would be a good idea to add the following lines in createElm which just make sure
that the function doesn't want to access attributes of an undefined object:

if (typeof(vnode) === 'undefined') {
    return
}

This seems to solve the problem for Vue 2.1.7 and also Vue 2.1.6 when calling createElm(undefined, ...).

It should be analyzed where the error gets introduced (i.e. why createElm gets called with an undefined vnode), but I think it is a good idea to do type checking here regardless.
Maybe a unit test should be added to check for this case.

Would be glad to help.

[yyx990803]

This should actually be the same issue with #4564 and is fixed by #4572 (confirmed for @Darkside73 and @johnleider 's cases)

@mmochetti @samuelantonioli you can try the patch in #4572 in your local Vue dist file to see if they are the same issue - if the error persists, they are likely different bugs and please open separate issue with repro.

[samuelantonioli]

@johnleider

it seems that there's the same problem with missing type checking before accessing the attributes in your referenced issue #4584

The relevant part for this bug is here: src/core/instance/render.js#L293. Replacing the current if statement there with the following lines solves the problem for me (patching my local dist for testing):

if (
  typeof(child) === 'object' &&
  (child.context === context || child.functionalContext === context) &&
  child.data && (name = child.data.slot)
) {
    ...
}

[samuelantonioli]

@yyx990803 Thanks, after applying the changes to getNormalizationType, everything works as expected.