EXTRA_SEQUENTIAL_COLOR_SCHEMES result in error in color dropdown

[hbruch]

Defining EXTRA_SEQUENTIAL_COLOR_SCHEMES results in broken color dropdown.

How to reproduce the bug

1. In superset_config.py, define EXTRA_SEQUENTIAL_COLOR_SCHEMES, e.g. like

  EXTRA_SEQUENTIAL_COLOR_SCHEMES =[
    {
         "id": 'mySequentialScheme',
         "description": 'myDescription',
         "label": 'myLabel',
         "isDiverging": False,
         "colors":
          ['#dfdeeb', '#cac8dd', '#b5b2d0', '#a09dc2', 
           '#8d8ab6', '#7c79ab',
           '#6b69a0', '#5a5995', '#464889', '#2e367b']
    }
]

2. start superset
3. create a chart e.g. DeckGL polygon chart
4. In chart editor, Switch to Customize tab
5. See error in Color dropdown

Expected results

The defined extra colors should appear as a dropdown item.

Actual results

An unexpected error occures.

Screenshots

Environment

n.a.

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

Seems to have been introduced by refactorings of setupColors.ts