In ThermalStandard, we have reactive_power_limits::Union{Nothing, MinMax}. However, the exporter does reactive_power_limits.max without first checking whether it's nothing. A fix might look like

QT = if isnothing(reactive_power_limits)
            PSSE_DEFAULT
        else
            _warn_finite_default(
                reactive_power_limits.max;
                field_name = "QT",
                component_name = PSY.get_name(generator),
            )
        end

(or maybe we want PSSE_INFINITY, etc.). I am surprised we haven't already caught this.

Found by @mcllerena.