warn when config qml file is not valid.
warn when config qml file is not valid.

Change-Id: I5d029649b7c1f2e3f7686b975bd177d4d5f02588
Reviewed-on: http://codereview.qt-users.jp/974
Tested-by: qt-users.jp Jenkins
Reviewed-by: R Kake <cbc5d3388f71f248790a1304b32b99d60d92a3e5@gmail.com>
Tested-by: R Kake <cbc5d3388f71f248790a1304b32b99d60d92a3e5@gmail.com>
Reviewed-by: <42980d970444f9101663582e70cd53623b3238b4@gmail.com>

qt-users-jp/silk,qt-users-jp/silk,qt-users-jp/silk,qt-users-jp/silk