Obscure error in FF20

[Arnaud Didry]

Hi,

We are experiencing random and obscure errors since the FF20 update : "TypeError: Value does not implement interface Element".

The stack trace always point to the same line of code : `if (node.id && !node.id.tagName && !node.id.item) {id = node.id;}` (from YUI3 [1]). The caller also ensure that `node.nodeType === 1` [2]

Another particularity of the bug is that it seems to always occurs inside an IndexedDB callback.

We're still trying to find a way to produce a failing test case. We deployed a patch which wrap the line in a try/catch to log the `node` variable but since then the error doesn't seems to occur anymore.

It seems related to the bug #821606 [3]. Do you think of something else which can cause this ?

Should I file a ticket on bugzilla ?

Thanks !

Arnaud


[1] https://github.com/yui/yui3/blob/v3.8.0/src/dom/js/dom-core.js#L62-L63
[2] https://github.com/yui/yui3/blob/v3.8.0/src/dom/js/selector-native.js#L220
[3] https://bugzilla.mozilla.org/show_bug.cgi?id=821606

[Boris Zbarsky]

On 4/12/13 6:49 AM, Arnaud Didry wrote:
> We are experiencing random and obscure errors since the FF20 update : "TypeError: Value does not implement interface Element".

That's certainly the error you'd get if something that's not an element
has an element method called on it...

> The stack trace always point to the same line of code : `if (node.id && !node.id.tagName && !node.id.item) {id = node.id;}` (from YUI3 [1]). The caller also ensure that `node.nodeType === 1` [2]

That's quite odd, for sure!

Are you able to log any information about this when it fails? Knowing
node.localName would really help.

> We're still trying to find a way to produce a failing test case. We deployed a patch which wrap the line in a try/catch to log the `node` variable but since then the error doesn't seems to occur anymore.

_That_ indicates some sort of JIT bug to me, unfortunately. :( I guess
that answers my question about logging...

What if you put the try/catch higher up the callstack?

> Should I file a ticket on bugzilla ?

Please, with whatever information you have!

-Boris

[Arnaud Didry]

Hi Boris,

Thank you for your response, I filed a ticket on bugzilla : https://bugzilla.mozilla.org/show_bug.cgi?id=861947

We don't have much more informations, but we're now sure that the error happens on this check `node.id.tagName`. Hope this helps a little.

For now we are going to monkey patch YUI3 to remove the checks against IE<8 for FF20.

Thanks

Arnaud

[Boris Zbarsky]

On 4/15/13 1:08 PM, Arnaud Didry wrote:
> Thank you for your response, I filed a ticket on bugzilla : https://bugzilla.mozilla.org/show_bug.cgi?id=861947

Thank you. Let's follow up there....

-Boris