No trainer crash protection broken (again)

[SonicSBL]

Describe the bug
When entering a pro trainer for songs with no lessons, the game crashes.

To Reproduce
Steps to reproduce the behavior:

1. Go to "Training" on pro guitar or pro keys.
2. Click on "Learn a Song."
3. Select a song with no lessons (e.g. Ghostbusters).
4. Crash.

Expected behavior
The game should kick you back to the menu and tell you that there are no lessons for the song.

Screenshots
N/A

DX Settings

• dx_modifiers.txt
• dx_settings.txt
• dx_values.txt

Game Information

• Platform: PS3 w/ CFW
• Version: 6a60e3b
• Song Count: 708

Additional context
Same bug as #683