Error handling in new code model

The new code model does not skip over serious syntactical or semantic errors.
This means if there is an error the synchronization will stop until the error is resolved.

Issues go to the new output pane that is planned (https://intranet.qt.io/display/QTRD/Output+Pane) so the user is aware of it.

Midterm we can consider fixits for errors.

Syntactical issues can be caught by the tooling easily.
Currently, the most common issue is the removal of properties in components that are referenced too. With the new code model, the user would get immediate feedback in such a case. Ideally we would check such cases beforehand and not allow such breaking changes.

This issue is not critical in the context of Lite QML Designer but we should consider/plan the implications from the start.