code: function bundleError(res, statusCode, error, params) {
      var message = "Mendel: ";
      if (!error) {
          message += (statusCode === 404 ? 'Bundle not found' : 'Unable to create Bundle');
      } else {
          message += error.code + ' - ' + error.message;
      }
  
      debug([(error ? error.code : 'UNKNOWN'), 'hash=' + params.hash, 'bundle=' + params.bundle].join(' '));
  
      res.status(statusCode).send(message);
  }
docs: ****
  
  Here is a non-functional but more performant implementation of the same
  transformation above. I don't think it would pay off in performance, but
  I am keeping it here since I didn't benchmark. The above should be more
  maintainable.
  
  function indexedDeps(mods) {
  var i, key, deps, index, newId, newDeps, newMod, map, newMods;
  indexes can't start with 0 because 0 is false for browserify runtime
  map = [''];
  stores indexes
  for (i = 0; i < mods.length; i++) {
  if (mods[i].expose) continue;
  map.push(mods[i].id);
  }
  
  create new mods
  newMods = [];
  for (i = 0; i < mods.length; i++) {
  shallow copy original deps
  newMod = {};
  for(key in mods[i]) {
  newMod[key] = mods[i][key];
  }
  
  create new deps
  deps = mods[i].deps;
  newDeps = {};
  for(key in deps) {
  index = map.indexOf(deps[key]);
  if (index > -1) {
  newDeps[key] = index;
  } else {
  newDeps[key] = deps[key];
  }
  }
  
  replace props on new mod
  newId = map.indexOf(newMod.id);
  if (newId > -1) newMod.id = newId;
  newMod.deps = newDeps;
  newMods.push(newMod);
  }
  
  return newMods;
  }
  
  **