Support for the experimental syntax 'classProperties' isn't currently enabled (11:11):
Add
@babel/plugin-proposal-class-properties (
https://git.io/vb4SL) to the 'plugins' section of your Babel config to enable transformation.
If you want to leave it as-is, add
@babel/plugin-syntax-class-properties (
https://git.io/vb4yQ) to the 'plugins' section to enable parsing.