Hi
George,
Thanks
for using Syncfusion products.
We
have validated the scenario based on the screenshot you shared. The legend
click functionality in the donut chart is working as expected, we are unable to
replicate the reported console exception. For your reference, we have attached
the tested sample and corresponding screenshot.

Sample
: https://stackblitz.com/edit/react-j2t9643w?file=index.js
To
assist you further and identify the root cause more effectively, kindly provide
the following details:
- The complete code snippet with full chart
configuration.
- The locale setting used in your application.
- Information on whether any custom logic is implemented
for legend click through event handling.
Please
let us know if you have any further questions or concerns.
Regards,
Durga
Gopalakrishnan.