createObject() warning points to wrong line

In https://testresults.qt.io/logs/qt/qtquickcontrols2/8df96961c6a2d32cd6ce2f4136f2eb519e2b8d00/LinuxUbuntu_20_04x86_64LinuxUbuntu_20_04x86_64GCCqtci-linux-Ubuntu-20.04-x86_64-50-8beb0cSccache/36f92a4307d63f63dfb177aa56599128defe894e/test_1620131131/log.txt.gz

there is a warning:

agent:2021/05/04 09:24:41 build.go:379: 2: QWARN : tst_controls::Basic::RangeSlider::test_valueAt(0.0..1.0) qrc:/qt-project.org/imports/QtTest/TestCase.qml:672: Error: Cannot assign [undefined] to double

It's pointing to the return statement and not createObject() itself:

https://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/imports/testlib/TestCase.qml#n672

If I add debug output to createTemporaryObject(), I can see that the warning is produced by the createObject() call, but yet the warning always points to the return line after it.

The error itself is caused by passing undefined as one of the initial property values.