Error on missing onOutsideEvent

If I wrap an element that does not define an `onOutsideEvent` method, the following error is thrown

```
Component does not define "onOutsideEvent" method.
```
I can fix this by defining an empty method for `onOutsideEvent`. Would it be better to remove this error or issue a warning instead of an error?

Start by reproducing the error when a wrapped element lacks an onOutsideEvent method, then inspect the component implementation that raises it. The issue does not name a file or test; work is done only after the project settles whether this should remain an error, become a warning, or be removed, with coverage for that decision.

Written by the indexing model from the issue text.