fix div/0 in LuaExpressionTransform::PositionItem

stepmania/src/ActorScroller.cpp

@@ -131,7 +131,7 @@ void ActorScroller::LoadFromNode( const CString &sDir, const XNode *pNode )
 	float fItemPaddingStart = 0;
 	float fItemPaddingEnd = 0;
 	CString sTransformFunction;
-	int iSubdivisions = 0;
+	int iSubdivisions = 1;
 
 	GET_VALUE( "SecondsPerItem", fSecondsPerItem );
 	GET_VALUE( "NumItemsToDraw", fNumItemsToDraw );

stepmania/src/LuaExpressionTransform.cpp

@@ -11,6 +11,7 @@ LuaExpressionTransform::LuaExpressionTransform()
 
 void LuaExpressionTransform::SetFromExpression( const CString &sExpression, int iNumSubdivisions )
 {
+	ASSERT( iNumSubdivisions > 0 );
 	m_pexprTransformFunction->SetFromExpression( sExpression );
 	m_iNumSubdivisions = iNumSubdivisions;
 }