Error using multiple tickets

Hi, so we were using multiple tickets. Specifically SPY and TESLA. And the problem is that when the backtest it's working, this error appears: 

class BootCampTask(QCAlgorithm):
    # Order ticket for our stop order, Datetime when stop order was last hit
    stopMarketTicket = None
    stopMarketOrderFillTime = datetime.min
    highestTSLAPrice = 0
    openingBar = None 
        
    def Initialize(self):
        self.SetStartDate(2017, 10, 2)
        self.SetEndDate(2019, 5, 30)
        self.SetCash(100000)
        self.SetSecurityInitializer(self.CustomSecurityInitializer)
        
        tickers = ['SPY','TSLA']
        self.symbol_data_by_symbol = {}
        for ticker in tickers:
            openingBar = None 
            symbol = self.AddEquity(ticker, Resolution.Minute).Symbol
            self.symbol_data_by_symbol[symbol] = SymbolData()
            self.Consolidate(symbol, timedelta(minutes=30), self.OnDataConsolidated)
            self.Schedule.On(self.DateRules.EveryDay(symbol), self.TimeRules.At(13,30), self.ClosePositions)
        #3. Create a scheduled event triggered at 13:30 calling the ClosePositions function

    def CustomSecurityInitializer(self, security):
        security.SetDataNormalizationMode(DataNormalizationMode.Raw)
            
    def OnData(self, data):
        if self.openingBar is None:
            return
        for symbol, symbol_data in self.symbol_data_by_symbol.items():
            if not data.ContainsKey(symbol) or data[symbol] is None:
                continue
                  
            if data[symbol].Close > self.openingBar.High and not self.Portfolio.Invested:
                quantity = self.CalculateOrderQuantity(symbol, 0.45)
                self.MarketOrder(symbol, quantity) # orders 45% of portfolio
                self.stopMarketTicket = self.StopMarketOrder(symbol, -self.Portfolio[symbol].Quantity, data[symbol].Close * 0.9)
                
            if self.Portfolio.Invested and data[symbol].Close > self.highestTSLAPrice:
                self.highestTSLAPrice = self.Securities[symbol].Close
                updateFields = UpdateOrderFields()
                updateFields.StopPrice = self.highestTSLAPrice * 0.9
                self.stopMarketTicket.Update(updateFields)
            
    def OnOrderEvent(self, orderEvent):
        if orderEvent.Status != OrderStatus.Filled:
            self.openingBar = None
            return
        if self.stopMarketTicket is not None and self.stopMarketTicket.OrderId == orderEvent.OrderId:
            self.stopMarketOrderFillTime = self.Time
            
    def OnDataConsolidated(self, bar):
        self.Log(f"Bar at {self.Time} for {bar.Symbol}")
        if bar.Time.hour == 9 and bar.Time.minute == 30:
            self.openingBar = bar
            
    def ClosePositions(self):
        #2. Set self.openingBar to None, and liquidate TSLA
        self.openingBar = None
        self.Liquidate() # liquidate entire portfolio

        
class SymbolData:
    def __init__(self):
        # Order ticket for our stop order, Datetime when stop order was last hit
        stopMarketTicket = None
        stopMarketOrderFillTime = datetime.min
        highestPrice = 0
        openingBar = None
            

This is the code. And the information required only appears for a single ticket, in this case only for TSLA. Thanks!!