"Failed to write uninstaller information" error when quitting installer on LicencePanel

If the installer uses LicencePanel as the first panel, clicking quit before accepting licence results in "Failed to write uninstaller information" pop-up.

Since both next and previous buttons are disabled, InstallerFrame#quit thinks the installation has been complete and attempts to write out uninstaller. However since the TargetPanel has not been executed yet, installation path is unknown and attempt to write the jar into it fails with NPE.

Possibly a solution might be
1. Always using ConfirmQuitType.CONFIRM on first Panel
2. Adding a check if install path is set in the InstallerFrame#quit to determine if installation was complete