Method shift

deps/undici/src/lib/dispatcher/fixed-queue.js:125–134

@returns {T|null}

()

  /** @returns {T|null} */
  shift () {
    const tail = this.tail
    const next = tail.shift()
    if (tail.isEmpty() && tail.next !== null) {
      // If there is another queue, it forms the new tail.
      this.tail = tail.next
      tail.next = null
    }
    return next
  }
}