Legacy Sunburst chart not rendering when secondary_metrics is null in 3.0.0rc3

[zhaorui2022]

While going through some legacy charts already exist in database. Sunburst charts no longer render in 3.0.0rc3, while it's working in 2.0.0.

How to reproduce the bug

I have tried to create a new sunburst chart but it seems the form data doesn't contain secondary_metrics with null as the value any more. However, we do have existing charts in production database contains such fields. In order to reproduce, we need to manually modify the chart from the backend db and add a null value for secondary_metrics.

1. Create a sunburst chart
2. Modify the chart from backend db and inject null as value for secondary_metrics.
3. Refresh chart
4. See error

Expected results

Sunburst chart renders as what it does in 2.0.0

Actual results

Chart complains about the null value and fails to render

Screenshots

In 3.0.0rc3

In 2.0.0

Environment

(please complete the following information):

• browser type and version: Chrome latest stable release
• superset version: superset version 3.0.0rc2
• python version: python --version 3.9
• node.js version: node -v N/A
• any feature flags active: I don't find any related feature flags

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

Additional context

Add any other context about the problem here.

[zhaorui2022]

I just took another look at the broken ones, they seemed to be created 1 or 2 yrs ago. So maybe the secondary_metrics field was there in an older version?