karma-webpack-tape: Show Line Number when Test Fails

Question

As the title implies, I want to be able to see the line number when a test fails in my suite. I'm relying on the karma-tap plugin, the tap framework, and dots reporter.

A little context: source-maps are working properly, so exceptions thrown in a test file report the correct line as well as a stack trace. However, when a basic test fails, the "failed" message is outputted without anything about the line or module.

Chrome 50.0.2661 (Mac OS X 10.11.4)  should be equal FAILED
    {
      "operator": "equal",
      "expected": 0,
      "actual": 1
    }
Chrome 50.0.2661 (Mac OS X 10.11.4)  should be equal FAILED
    {
      "operator": "equal",
      "expected": 0,
      "actual": 1
    }
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My initial thought was that this is just a limitation of Tap, but I can't imagine that's true. My full Karma config is shown below. Is there something in the configuration that would cause the output of line numbers during a test to fail?

{
    plugins: [
      require('karma-webpack'),
      require('karma-tap'),
      require('karma-chrome-launcher'),
      require('karma-sourcemap-loader')
    ],

    basePath: '',
    frameworks: [ 'tap' ],
    files: [
      'tests.bootstrap.js',
    ],
    preprocessors: {
      'src/**/*.js': ['webpack', 'sourcemap'],
      'tests.bootstrap.js': [ 'webpack', 'sourcemap' ]
    },
    webpack: {
      devtool: 'inline-source-map',
      externals: {
       cheerio: 'window',
       'react/lib/ExecutionEnvironment': true,
       'react/lib/ReactContext': true,
       'text-encoding': 'window',
       'react/addons': true,
      },
      module: {
        preLoaders: [
          {
            test: /\.js/,
            exclude: /node_modules/,
            loader: 'babel'
          },
          {
            test: /\.js$/,
            include: [
              path.resolve(__dirname, 'src/components/'),
              //path.resolve(__dirname, 'src/containers/'),
              path.resolve(__dirname, 'src/layouts/'),
              path.resolve(__dirname, 'src/reducers/'),
              path.resolve(__dirname, 'src/stores/'),
              path.resolve(__dirname, 'src/util/')
            ],
            exclude: /-container\.js/,
            loader: 'isparta'
          }
        ],
        loaders: [
          {
            test: /\.js$/,
            exclude: /node_modules/,
            loader: "source-map-loader"
          }, {
            test: /\.(png|jpg|jpeg|gif|woff|woff2)$/,
            loader: 'url?limit=25000',
            include: path.resolve(__dirname, 'src')
          }, {
            test: /\.svg$/,
            loader: 'file-loader'
          }
        ]
      },
      node : {
        fs: 'empty'
      },
      resolve: {
        modulesDirectories: ['src', 'node_modules']
      }
    },

    webpackMiddleware: {
      noInfo: true
    },

    reporters: [ 'dots' ],

    client: {
      captureConsole: false
    },

    port: 9878,
    colors: true,
    logLevel: config.LOG_DEBUG,
    autoWatch: true,
    browsers: ['Chrome'],
    singleRun: false
  }