Creator crashes when adding CPP header or source to existing project

Steps to reproduce:

• create a Qt Widgets Application or Empty Qt Project
• add a C++ file to it (File -> New File or Project... -> C++ -> C++ Header)
• hit 'Next' after giving the file a name

Current result:

• Creator crashes

Note: introduced with 2ad3147542a45436733ddd7014993bcc3022a654