使用sourcemap调试chrome上的缩小js（uglifyjsplugin / webpack）

Question

我正在使用webpack2在javascript中编写应用程序，当我尝试调试webpack uglify（webpack -p）生成的缩小代码时，我遇到了大问题， chrome控制台无法评估变量。

webpack.config.js

var webpack = require("webpack");
var path = require("path");
var package = require("./package");

module.exports = {
    devtool: "source-map",
    entry: "./app.js",
    output: {
        path: path.join(__dirname, "build"),
        filename: "app-" + package.version + ".js"
    }
};

app.js

var firstLetter = "a";
var secondLetter = "b";

teste(firstLetter + secondLetter);

function teste(msg) {
    var msgAlert = msg + "c";
    alert(msgAlert);
}

console evaluate problem screenshot

这是正常的浏览器行为吗？

提前致谢。