fix(SecureViewService): handle fopen() returning false for non-existent paths

When shouldSecure() is called with tryOpen=true on a path that does not
exist yet (e.g. a rename target or a files_versions snapshot path), the
underlying fopen() call returns false. Calling fclose(false) on that
value throws a TypeError in PHP 8, which propagates as an uncaught
exception and aborts the entire DAV operation with HTTP 500.

To reproduce: enable Secure View watermarking for a group, add your
user to that group, then rename or overwrite any Office document. The
rename fails immediately with HTTP 500 and the following error appears
in nextcloud.log:

  fclose(): Argument #1 ($stream) must be of type resource, bool given
  in …/richdocuments/lib/Service/SecureViewService.php:37

Signed-off-by: Christoph Schaefer <christoph.schaefer@nextcloud.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: chrip

lib/Service/SecureViewService.php

@@ -34,6 +34,12 @@ public function shouldSecure(string $path, IStorage $storage, bool $tryOpen = tr
 		if ($tryOpen) {
 			// pity… fopen() does not document any possible Exceptions
 			$fp = $storage->fopen($path, 'r');
+			if ($fp === false) {
+				// File does not exist yet (e.g. rename target or version snapshot).
+				// Assume the target will be in a secure context so that rename/copy
+				// is not blocked by checkSourceAndTarget.
+				return true;
+			}
 			fclose($fp);
 		}