QuickDesigner: QC crashes when switching to Designer while project is read

Steps to reproduce:

• start Qt Creator, create a Qt Quick Application (I've used with Controls 1.2, having a valid Qt5.3.2 kit configured) from template
• as soon QC displays the QML file inside the editor switch to Design mode (Progress bar regarding 'Reading Project XYZ' must be still displayed and unfinished..)

Current result:

• QC crashes [see attached log]

Note: this seems to be caused by the now asynchronous reading of the project. If you wait until the progress bar has finished, this works without crashing.