Nested templates throwing exceptions with reference to observe.js

[michaelsbradleyjr]

May be related to #263 and #235(ShadowDOM).

Try the following sample-code (written by my co-worker) with both the 8/29 and 8/15 releases of Polymer:

https://gist.github.com/mattmoss/6395526

It works with the older release, but with the newer one will throw exceptions when the columns are clicked, for example:

"Exception caught during observer callback: NotFoundError: An attempt was made to reference a Node in a context where it does not exist. observe.js:341"

"Exception caught during observer callback: TypeError: Cannot call method 'schedule' of undefined observe.js:341"

"Uncaught TypeError: Cannot call method 'schedule' of undefined."

[sjmiles]

If you run (Chrome) Canary with Experimental WebKit Features enabled, then you should have native ShadowDOM. Are you running with native ShadowDOM? If it works with native, then the problem is with the ShadowDOM Polyfill, and this is a likely a dupe of this root cause: Polymer/ShadowDOM#235.

Also, fwiw, and unfortunately, the observe.js:341 information is basically wrong. Unhandled exceptions are fatal for observe.js, so the system protects itself with a try/catch block. observe.js re-throws the exception when it is safe, which causes the console debugger to report an error in observe.js. This is something we would like to improve, but that's how it's set up as of now.

[michaelsbradleyjr]

Indeed, after enabling experimental Web Platform features for Chrome Canary in chrome://flags, exceptions are not thrown as before, and the sample code behaves as expected.

Thanks for the tip and explanations.

[michaelsbradleyjr]

This issue seems to have been resolved as of today's release. Here's the code linked above in a jsbin, loading the 0905 release -- works fine:

http://jsbin.com/UPoVAjA/2/edit