TypeError: Cannot read property 'browser_version' of undefined

[Krinkle]

Expected Behavior

Test against firefox_45, safari_9, safari_10, safari_11.

Actual Behavior

/browserstack-runner/bin/cli.js:401
            if (browser.browser_version === 'latest') {
                        ^

TypeError: Cannot read property 'browser_version' of undefined
    at /qunit/node_modules/browserstack-runner/bin/cli.js
    at Array.forEach (<anonymous>)
    at /qunit/node_modules/browserstack-runner/bin/cli.js
    at Timeout._onTimeout (/qunit/node_modules/browserstack-runner/lib/local.js)

browserstack.json

  "browsers": [
    "safari_9"
  ],

Platform details

• browserstack-runner version: 0.9.4
• node version: 10.x

[Krinkle]

After a long time debugging and narrowing down, I found that the following happens for safari_9:

  getBrowserObject: function(entry) {
    var browserObject = {};
    var version = null;
    var sliceStart = 1;
    if (typeof entry  === 'string') {
      // …
      if (browserData[lindex] && browserData[lindex].indexOf('+') === -1) {
        if (['current', 'previous', 'latest'].indexOf(browserData[lindex]) !== -1) {
          // …
        } else {
          version = browserData.slice(sliceStart, lindex + 1).join('.'); // <!-- assign "9"
        }
      } else {
        // …
      }
      if (browserObject.mobile) {
        // …
      } else {
        browserObject.browser_version = version; // <!-- assign "9"
      }
    } else {
      // …
    }
    browserObject = ConfigParser.populateOsAndOsVersion(browserObject); // <!-- assign undefined
    return browserObject;
  }

  populateOsAndOsVersion: function(browserObject) {
    if (!(browserObject.os && browserObject.os_version)) {
      if (browserObject.mobile) {
        // …
      } else {
        // …;
        var osxFiltered = ConfigParser.bsBrowsers.filter(function(currentValue) {
          return currentValue.os === 'OS X' && currentValue.browser === browserObject.browser && ((browserObject.browser_version && browserObject.browser_version.indexOf('latest')) > -1 || parseFloat(currentValue.browser_version).toPrecision(4) === parseFloat(browserObject.browser_version).toPrecision(4));
        });
        // ^ osxFiltered is []

        var filteredObject = osxFiltered[Math.floor(Math.random() * osxFiltered.length)];
        // ^ filteredObject ==> osxFiltered[0] ==> undefined
   
        browserObject = filteredObject;
      }
    }
    return browserObject;
  }

I thought that 9 means 9.x but it actually means 9.0 so the user has to make sure the version matches exactly with that of https://www.browserstack.com/list-of-browsers-and-platforms/js_testing. I'll leave aside whether that is the intend behaviour but at the least we should tell make sure browserstack-runner does not crash and gives the user a useful error message.