Load a tile with full fetchOptions.

This is only used when the Authorization header has been set
in the fetchOptions.

@param {Object} fetchOptions Options to use for fetch calls.

@returns {Function} Tile loading function which uses fetch.
function authTileLoader(fetchOptions) {
  return function(tile, src) {
    fetch(src, fetchOptions)
      .then(r => r.blob())
      .then((imgData) => {
        tile.getImage().src = URL.createObjectURL(imgData);
      })
      .catch(() => {
        console.error('Error fetchimg image at:', src);
      });
  };
}