ERROR in ./app/main.js Module build failed (from ./node_modules/babel-loader/lib/index.js): Error: Plugin/Preset files are not allowed to export objects, only functions. In /home/littleboy/myProject/myWebPackDemo/node_modules/babel-preset-react/lib/index.js at createDescriptor (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-descriptors.js:178:11) at items.map (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-descriptors.js:109:50) at Array.map (<anonymous>) at createDescriptors (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-descriptors.js:109:29) at createPresetDescriptors (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-descriptors.js:101:10) at passPerPreset (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-descriptors.js:58:96) at cachedFunction (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/caching.js:33:19) at presets.presets (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-descriptors.js:29:84) at mergeChainOpts (/home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-chain.js:320:26) at /home/littleboy/myProject/myWebPackDemo/node_modules/@babel/core/lib/config/config-chain.js:283:7 @ multi (webpack)-dev-server/client?http://0.0.0.0:8080 ./app/main.js main[1]