readUint53() {
    const { low32, high32 } = this.readUint64()
    if (high32 < 0 || high32 > 0x1fffff) {
      throw new RangeError("number out of range")
    }
    return high32 * 0x100000000 + low32
  }
Reads a LEB128-encoded unsigned integer from the current position in the
buffer. Allows any integer that can be safely represented by JavaScript
(up to 2^53 - 1), and throws an exception outside of that range.