openmc.settings.track does not always validate input

[MicahGale]

Bug Description

If you set openmc.settings.track to a nonsensical value it can sometimes raise no errors and export the values while having no impact on what is actually exported to xml.

Steps to Reproduce

MWE:

import openmc
model = openmc.Model()
model.settings.track = it.chain(*[[(j, 1, n) for n in range(1, 10_000)] for j in range(80, 101)])
model.export_to_xml()

The subsequent XML file then has <track></track>, with no warnings or errors.

Environment

• Openmc 0.14.0