readUint8Array = (decoder, len) => {
  const view = buffer.createUint8ArrayViewFromArrayBuffer(decoder.arr.buffer, decoder.pos + decoder.arr.byteOffset, len);
  decoder.pos += len;
  return view;
}
Create an Uint8Array view of the next `len` bytes and advance the position by `len`.

Important: The Uint8Array still points to the underlying ArrayBuffer. Make sure to discard the result as soon as possible to prevent any memory leaks.
           Use `buffer.copyUint8Array` to copy the result into a new Uint8Array.

@function
@param {Decoder} decoder The decoder instance
@param {number} len The length of bytes to read
@return {Uint8Array}