JsDiff.diffWords('', ' ');
// Uncaught TypeError: Cannot read property 'value' of undefined

function buildValues
// …
var lastComponent = components[componentLen - 1];
      if ((lastComponent.added || lastComponent.removed) && diff.equals('', lastComponent.value)) {
        components[componentLen - 2].value += lastComponent.value; // < here
        components.pop();
      }