Wizards: Strange behaviour of Project Details selection

Steps to reproduce:

• start QC, make sure you're having no kit configured using Qt5.3+ (any Qt version below 5.3 should be fine to reproduce this issue)
• invoke 'File' -> 'New File or Project...' -> 'Application' -> 'Qt Quick Application'
• specify a valid project location
• on the Project Details page: leave minimal required Qt version to be unset
• click Next

Expected behaviour:

• if it's not possible to set a minimal required Qt version, the 'Next' button should be disabled

additionally I had this on the cmdline

"Error in \" .qtQuickVersion\": SyntaxError: Syntax error"