Reporting gaps in resource profiles

Checked for duplicates

Yes - I've already checked

Alternatives considered

Yes - and alternatives don't suffice

Related problems

No response

Describe the feature request

There are some instances where it doesn't make sense for a model to report a resource value. At the moment, we have two use cases:

1. A resource is not applicable to the current circumstances. For example, a resource tracking where on the ground a surface-observing instrument is pointed should be "N/A" or some equivalent if the instrument is not currently pointed at the ground.
2. A resource has failed, but the simulation continues. For example, the telecom model might fail while the power model continues working, and we'd like to report values for the power resources.

In both of these cases, we'd like to report either a "gap" in the resource profile, or some different type of value, distinct from normal values for that resource.

Start by locating the resource-profile entry point and the path that reports resource values; the issue names no files or tests. Done means the project has a defined way to distinguish unavailable or failed resource values from normal values while allowing other simulation resources to continue reporting.