code: function build_dist_sourcemap(){
    // run webpack
    return gulp.src('index.js').pipe(webpackStream(createWebpackConfig({
      mode: 'development',
      entry: classicEntry,
      output: {
          filename:'oidc-client.js',
          libraryTarget:'var',
          library:'Oidc'
      },
      plugins: [],
      devtool:'inline-source-map'
    }), webpack))
    .pipe(gulp.dest('dist/'));
  }
docs: classic build with sourcemaps