[Obs Alerting] Fix null value warning for metric threshold preview chart

[maryam-saeidi]

UPDATE: We won't fix this in particular bug in the metric threshold rule, but we want to check other rules to see if a similar error is occurring and whether using NaN instead of null might solve the problem. More in this comment below.

📝 Summary

When in the chart data there are null values, a warning is shown in the console.

✅ Acceptance Criteria

• Fix the above-mentioned warning

[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)

[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)

[jasonrhodes]

@maryam-saeidi do we know if this is still an issue?

[maryam-saeidi]

@jasonrhodes Yes, it is still the case when I stop generating data, I will see this warning in the developer console but I don't know if we really want to invest time in the metric threshold preview chart, I would vote for closing this ticket.

[maryam-saeidi]

@jasonrhodes To give you a bit more context, I saw this ticket that was similar to our case and I asked about it in Slack from charts team and the suggestion was to use NaN instead of null and it might help with this issue (comment)

Now, we are using a lens embeddable in the custom threshold rule's preview, so I suspect this issue is more relevant to the other rules that use the charts package directly. Maybe we should check other charts as well and if we have this issue in other places, we can come up with a generic approach to fix it everywhere.

[jasonrhodes]

@maryam-saeidi sounds good, I added an update to the top of this issue description and then moved it to "Refining" status. If we discover there are other rules that need a fix and that NaN fixes it, let's create a new issue for that. Either way, once we've checked the other rules, we should close this issue.

[jasonrhodes]

Closing this as it's been sitting for a while.