Blank screen and no error if custom element is not registered

[lavelle]

Creating a new element

<polymer-element name="my-foo"></polymer-element>

without declaring it with

Polymer('my-foo', {});

causes the entire page to fail to render. No errors are displayed in the console, and while the correct DOM tree is present, nothing is visible. Native elements like div and h1 have the correct dimensions and position, when highlighted with the Chrome inspector, whereas all custom elements have height and width zero, regardless of their styling.

Ideally, other elements on the page should be immune to this, leaving only the undefined element unrendered. At the very least, however, an error should be logged to the console warning that a custom element has been declared in the HTML but not registered in JS.

[lavelle]

cc @jmuk

[sorvell]

Related to https://github.com/Polymer/polymer-dev/issues/72

[sorvell]

We've added a couple basic tools that can help debug this situation. This is not enough, but it can help. The current plan is to integrate these low level tools into the Polymer dev tools extension to enable convenient debugging.

Polymer.waitingFor() returns the list of elements that polymer is waiting for before registering a set of definitions.

Polymer.forceReady(timeout) force polymer to register whatever it can register after an optional timeout in milliseconds.

[tjsavage]

Closing this issue due to age and the release of version 1 of Polymer - please feel free to re-open if this is incorrect.