.map files in built directory cause stacktrace lines to nowhere

[pittgoose]

When I got a timeout from protractor, the stacktrace included lines pointing to TypeScript files but those files are not published. Example:

ScriptTimeoutError: asynchronous script timeout: result was not received in 45 seconds
  (Session info: chrome=58.0.3029.83)
  (Driver info: chromedriver=2.29.461571 (8a88bbe0775e2a23afda0ceaf2ef7ee74e822cc5),platform=Linux 3.19.8-100.fc20.x86_64 x86_64)
    at WebDriverError (/<redacted>/node_modules/selenium-webdriver/lib/error.js:27:5)
    at ScriptTimeoutError (/<redacted>/node_modules/selenium-webdriver/lib/error.js:203:5)
    at Object.checkLegacyResponse (/<redacted>/node_modules/selenium-webdriver/lib/error.js:505:15)
    at parseHttpResponse (/<redacted>/node_modules/selenium-webdriver/lib/http.js:509:13)
    at doSend.then.response (/<redacted>/node_modules/selenium-webdriver/lib/http.js:440:13)
    at process._tickCallback (internal/process/next_tick.js:103:7)
From: Task: Protractor.waitForAngular() - Locator: By(css selector, .leaflet-marker-icon)
    at WebDriver.schedule (/<redacted>/node_modules/selenium-webdriver/lib/webdriver.js:816:17)
    at ProtractorBrowser.executeAsyncScript_ (/<redacted>/node_modules/protractor/lib/browser.ts:608:24)
    at angularAppRoot.then (/<redacted>/node_modules/protractor/lib/browser.ts:642:23)
    at ManagedPromise.invokeCallback_ (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:1366:14)
    at TaskQueue.execute_ (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2970:14)
    at TaskQueue.executeNext_ (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2953:27)
    at asyncRun (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2813:27)
    at /<redacted>/node_modules/selenium-webdriver/lib/promise.js:676:7
    at process._tickCallback (internal/process/next_tick.js:103:7)
From: Task: <anonymous>
    at pollCondition (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2101:19)
    at /<redacted>/node_modules/selenium-webdriver/lib/promise.js:2097:7
    at new ManagedPromise (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:1067:7)
    at ControlFlow.promise (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2396:12)
    at /<redacted>/node_modules/selenium-webdriver/lib/promise.js:2096:22
    at TaskQueue.execute_ (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2970:14)
    at TaskQueue.executeNext_ (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2953:27)
    at asyncRun (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2860:25)
    at /<redacted>/node_modules/selenium-webdriver/lib/promise.js:676:7
    at process._tickCallback (internal/process/next_tick.js:103:7)
From: Task: Expected element 'By(css selector, .leaflet-marker-icon)' to be visible within 20 seconds.
    at scheduleWait (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2094:20)
    at ControlFlow.wait (/<redacted>/node_modules/selenium-webdriver/lib/promise.js:2408:12)
    at WebDriver.wait (/<redacted>/node_modules/selenium-webdriver/lib/webdriver.js:943:29)
    at run (/<redacted>/node_modules/protractor/lib/browser.ts:66:27)
    at ProtractorBrowser.to.(anonymous function) [as wait] (/<redacted>/node_modules/protractor/lib/browser.ts:74:12)

As you can see there are several references to /node_modules/protractor/lib/browser.ts. The fix for this is adding built/**/*.map to the .npmignore file so that the maps are there for dev but not production.