Be more picky if qmltype information is missing

The attached example contains a little, non obvious misconfiguration, which took me hours to nail down. Compiling the example claims:

[ 70%] Built target sample_nativeplugin_init
[ 72%] Running moc --collect-json for target sample
[ 74%] Automatic QML type registration for target sample
[ 76%] Generating .rcc/qmlcache/sample_main_qml.cpp
Warning: main.qml:12:17: Cannot assign binding of type UIInterface to QObject
        target: FB.UIInterface
                ^^^^^^^^^^^^^^
Error: main.qml:12:31: Could not compile binding for target: cannot convert from UIInterface of UIInterface to QObject of QObject
        function onPasswordResult(res : string) {
        }
    }
}


                                                                    ^
[ 78%] Running rcc for resource qmake_base
[ 80%] Running rcc for resource sample_raw_qml_0

The compiler echos almost everything of the file following the error. I had nearly complete qml files in the build log output.

Although everything looks more or less fine and the app compiles at the first glance, you'll notice that the src/app/foo/CMakeLists.txt lacks a "core" link target. And you'll notice that the only reason why the app actually links, is that "core" is linked to "model", and the missing symbols are coming in this way.

For whatever reason, the qmltypes are incomplete if not being linked to "core". If there's an easy way to detect that, it could save time. If not, just close it