build failed cause of plugin-proposal-decorators

[mico]

After running yarn build I got:

    ERROR in ./src/main/index.js
    Module build failed (from ./node_modules/babel-loader/lib/index.js):
    Error: [BABEL] /Users/mico/Projects/pathephone-desktop/src/main/index.js: The decorators plugin requires a 'decoratorsBeforeExport' option, whose value must be a boolean. If you want to use the legacy decorators semantics, you can set the 'legacy: true' option. (While processing: "base$2")
        at _default (/Users/mico/Projects/pathephone-desktop/node_modules/@babel/plugin-proposal-decorators/lib/index.js:50:13)