Helm's Flow datasource cannot filter "NaN" results, breaking Grafana reduce expressions

The OpenNMS Flows API inserts "NaN" for any cell in the result set that doesn't have a value.
Grafana's reduce expressions will always return "NaN" if any values are null or NaN.

Expected result:
Helm should provide a way to filter "NaN" from the results returned by OpenNMS, so reducing expressions can be applied to them.

Actual result:
Any data set that includes "NaN" cannot be reduced.

Could add a nonNull() query transform, similar to the groupByInterval() one.