Check order of calling of variables in OnStart

[pgleeson]

For example of how this can be an issue see:
https://github.com/OpenSourceBrain/WangBuzsaki1996/blob/master/NeuroML2/LEMS_ComponentType/LEMS_WangBuzsaki.xml
https://github.com/OpenSourceBrain/WangBuzsaki1996/blob/master/NeuroML2/LEMS_ComponentType/.test.wb.pylemsnml2.omt.disabled