getting a few errors thrown up when trying to debug strategy with Visual Studio (see attached) - is this my fault or should I find another debug method?
Probabily, the exception is thrown because owner is null. You should check that "owner as Gui.NinjaScript.IChartBars" is not null before reference it.
This is likely the case, or one of the objects in that line is null. Generally with Visual studio you can hover the mouse cursor over each object to see if it has a value or if it is null to determine what specifically is null.
Otherwise checking each object that can be null if it is not null should also correct this.
I look forward to being of further assistance.