callback-repro.js

function runTest() {
  console.log("making ajax call");
  $.ajax({
    url: "/failing"
  }).fail(function(result) {
    console.log("in fail");
    console.log("_rollbar:", _rollbar);
    return _rollbar.push('TEST', function() {
      console.log("in callback");
      return alert('TEST');
    });
  });
}
// this works
setTimeout(runTest, 1000);

// this does not
runTest();