Hi Curtis,
Thank you for contacting Syncfusion support.
We are able to reproduce the issue with “Incorrect Typing in onclick event in the React base” in our end. So, we have logged a defect report for the same and the fix will be included in our Essential Studio 2018 Volume 4 Service Pack-1 release which will be expected to be release in the month of January, 2019.
We appreciate your patience until then.
Thanks,
Christo