Fix issue 585: editor crash w/o saving.

This does not feel like a proper cure, but it does
stop the crashing.

Docs/Changelog_sm5.txt

@@ -8,6 +8,11 @@ ________________________________________________________________________________
 StepMania 5.0 $next | 2011xxxx
 --------------------------------------------------------------------------------
 
+2011/10/17
+----------
+* [ScreenEdit/NoteField] Fix an editor crash when you exit without saving
+  after creating new steps. [Wolfman2000]
+
 2011/10/16
 ----------
 * [NoteDataUtil] Add the Backwards mod for games where the intended

src/NoteField.cpp

@@ -1079,6 +1079,9 @@ void NoteField::DrawPrimitives()
 			AttackArray &attacks = GAMESTATE->m_bIsUsingStepTiming ?
 				GAMESTATE->m_pCurSteps[PLAYER_1]->m_Attacks :
 				GAMESTATE->m_pCurSong->m_Attacks;
+			// XXX: We're somehow getting here when attacks is null. Find the actual cause later.
+			if (&attacks)
+			{
 				FOREACH_CONST(Attack, attacks, a)
 				{
 					float fBeat = timing.GetBeatFromElapsedTime(a->fStartSecond);
@@ -1090,6 +1093,7 @@ void NoteField::DrawPrimitives()
 					}
 				}
 			}
+		}
 
 		if( !GAMESTATE->m_bIsUsingStepTiming )
 		{