Merge pull request #33774 from nextcloud/hash-wrapper-closed-hash

handle cases where the hash context gets cleaned up before the hash wrapper

lib/private/Files/Stream/HashWrapper.php

@@ -67,7 +67,11 @@ public function stream_read($count) {
 
  public function stream_close() {
  if (is_callable($this->callback)) {
- call_user_func($this->callback, hash_final($this->hash));
+ // if the stream is closed as a result of the end-of-request GC, the hash context might be cleaned up before this stream
+ if ($this->hash instanceof \HashContext) {
+ $hash = hash_final($this->hash);
+ call_user_func($this->callback, $hash);
+ }
  // prevent further calls by potential PHP 7 GC ghosts
  $this->callback = null;
  }