If the image is update but null we still generate a new image. This
is a ugly workaround for the flaky generation process. Hopefully
we can fix it after all hidden dependencies are removed.
Change-Id: I0e344002a1952fb849393d3e245e31612c69d7bd
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>