Custom library - @angular-builders/custom-webpack:browser throw compile time warning ( angular8)

[HemTech]

I’m getting warning to compile angular 8 project with custom library

WARNING in C:/Project/.../fesm2015/customlibary.js.map 1:10 Module parse failed: Unexpected token (1:10) You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders