TypeError: Argument 1 passed to XF\Import\Data\ThreadPrefix::setTitle() must be of the type string, null given

[Kirby]

Code:

#0 src/addons/XFI/Import/Importer/vBulletin.php(2773): XF\Import\Data\ThreadPrefix->setTitle(NULL)
#1 src/XF/Import/Runner.php(242): XFI\Import\Importer\vBulletin->stepThreadPrefixes(Object(XF\Import\StepState), Array, 8)
#2 src/XF/Import/Runner.php(59): XF\Import\Runner->runStep('threadPrefixes', Object(XF\Import\StepState), 8)
#3 src/XF/Import/Runner.php(152): XF\Import\Runner->run()
#4 src/XF/Import/ParallelRunner.php(40)...

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