Missing signals and Runtime Error: Rolling window is empty

Hi

I'm trying to use a RollingWindow to look back on previous day's volatilities, so I have the following:

#...
		for tickers in self.tickers:
            self.volWindows[symbol] = RollingWindow[IndicatorDataPoint](5)
            self.volatilities[symbol].Updated += (lambda sender, updated: self.OnVolUpdated(sender, symbol, updated))
            
#...

    def OnVolUpdated(self, sender, symbol, updated):
        if self.volatilities[symbol].IsReady:
            self.volWindows[symbol].Add(updated)

To trigger a signal, I have the following:

if self.volWindows[symbol][1].Value > x:
	# ...

I've noticed that I'd frequently encountered the error: Runtime Error: Rolling window is empty (Parameter 'i') in RollingWindow.

I read that the readiness of `self.volWindows[symbol]` should be checked. But if I have

if self.volWindows[symbol].IsReady and self.volWindows[symbol][1].Value > x:
	# ...

Quite a few signals are omitted/skipped. Does anyone know how this could be rectified?

Thanks