Fix issue #3358495: Deprecated: explode(): Passing null to parameter #2...

Fix issue #3358495: Deprecated: explode(): Passing null to parameter #2 ($string) of type string is deprecated

src/Logger/DBLogFilter.php

@@ -49,7 +49,7 @@ class DBLogFilter extends DbLog {
     $severity_levels = $config->get('severity_levels');
     $entities_load = $config->get('log_values');
     $method = $config->get('method') ?: 'include';
-    $values = array_map('trim', explode("\n", $entities_load));
+    $values = array_map('trim', explode("\n", $entities_load ?? ''));
     foreach ($levels as $key => $log_level) {
       $level_array[$key] = strtolower($log_level->getUntranslatedString());
     }