A clear and concise description of what the bug is.

Expected results

Label type changed

Actual results

Label type doesn't changed

Screenshots

How to reproduce the bug

1. Go to 'Charts'
2. Click on 'any Pie chart.'
3. Change Label Type
4. See error

Environment

(please complete the following information):

• superset version: master
• python version: based on master
• node.js version: based on master

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.