Steps:
1. Create a qt quick project.
2. Edit the .qml file in designer mode.
3. Add an additional state "state1", and change some property in state one.
4. Change to editor mode and save the file.
5. Change to designer mode then turn back to editor mode.
6. Delete the States block, then save the .qml file.
7. Change to designer mode again, an error occured.
8. Change back to editor mode and edit( just add one empty line is OK ),then save this file.

Then Qt creator crashed.