Continue last session & play panel enabled

In both MS 1.0 and the nightly build, under Win7, I can crash MS quite handily through these steps:

1. Under Preferences, select "continue last session" and check "show" on "play panel"
2. Start a new score, but don't enter anything.
3. Quit (you should not be asked to save)
4. Relaunch MS. The play panel starts to come up, then MS crashes.

This could be related to #1722: Continue last session tries to open discarded score (regression) where, with "continue last session" enabled and doing steps 2 and 3 above, you still get the tab but a blank score window when MS reloads.