function createProjection(projection, defaultCode) {
  if (!projection) {
    return get(defaultCode);
  }
  if (typeof projection === 'string') {
    return get(projection);
  }
  return /** @type {Projection} */ (projection);
}
@param {Projection|string|undefined} projection Projection.
@param {string} defaultCode Default code.
@return {Projection} Projection.