Creator crashes when closing designer during build

(1) Create a new GUI project.
(2) Open the main window (mainwindow.ui) and drag a TextEdit onto it.
(3) Resize the TextEdit from the bottom right corner, for example, so that it occupies basically the whole client area.
(4) Save.
(5) Build the project and right after it, while the build is still going on, close the design editor. (Building with the shortcut instead of clicking on the menu should make it easier to reproduce.)
Result: Creator crashes.