webpack: switch devtool to eval-source-map, use in development mode only

webpack.config.js

@@ -1,8 +1,8 @@
 const path = require('path');
 
-module.exports = {
+module.exports = (env, argv) => {
+	let config = {
 		entry: './src/index.ts',
-	devtool: 'inline-source-map',
 		devServer: {
 			contentBase: './dist'
 		},
@@ -28,4 +28,11 @@ module.exports = {
 			filename: 'bundle.js',
 			path: path.resolve(__dirname, 'dist')
 		},
+	};
+
+	if (argv.mode === 'development') {
+		config.devtool = 'eval-source-map';
+	}
+
+	return config;
 };