Merge pull request #41425 from nextcloud/backport/41406/stable26

[stable26] fix(log): Log exception class when message is empty

lib/private/Log.php

@@ -338,7 +338,7 @@ public function logException(Throwable $exception, array $context = []) {
 		unset($data['app']);
 		unset($data['level']);
 		$data = array_merge($serializer->serializeException($exception), $data);
-		$data = $this->interpolateMessage($data, $context['message'] ?? '--', 'CustomMessage');
+		$data = $this->interpolateMessage($data, isset($context['message']) && $context['message'] !== '' ? $context['message'] : ('Exception thrown: ' . get_class($exception)), 'CustomMessage');
 
 
 		array_walk($context, [$this->normalizer, 'format']);