fixed

Closes #3421708

src/Plugin/ConfigFilter/ConfigSplitIgnoreFilter.php

@@ -169,7 +169,7 @@ class ConfigSplitIgnoreFilter extends IgnoreFilter {
    */
   public function filterExists($name, $exists) {
     // If the name is a deleted config, treat it as not existing.
-    if (in_array(static::DELETION_PREFIX . $name, $this->configuration['ignored'], TRUE)) {
+    if (!empty($this->configuration['ignored']) && in_array(static::DELETION_PREFIX . $name, $this->configuration['ignored'], TRUE)) {
       return FALSE;
     }
 
@@ -182,28 +182,24 @@ class ConfigSplitIgnoreFilter extends IgnoreFilter {
    * {@inheritdoc}
    */
   public function filterListAll($prefix, array $data) {
+    // Ensure $this->configuration['ignored'] is treated as an array.
+    $ignoredConfigs = !empty($this->configuration['ignored']) && is_array($this->configuration['ignored']) ? $this->configuration['ignored'] : [];
+
     foreach ($data as $key => $config_name) {
-      // If the name is a deleted config, treat it as not existing.
-      if (in_array(static::DELETION_PREFIX . $config_name, $this->configuration['ignored'], TRUE)) {
+      if (in_array(static::DELETION_PREFIX . $config_name, $ignoredConfigs, TRUE)) {
         unset($data[$key]);
       }
     }
-
-    if (!empty($this->getFilteredStorage()->getCollectionName())) {
-      // In collections, treat config as existing
-      // if it is ignored and exists in the active storage.
+  
+    if (!empty($this->getFilteredStorage()->getCollectionName()) && !empty($this->active)) {
       $active_names = $this->active->listAll($prefix);
-      $data = array_unique(array_merge($data, array_filter($active_names,
-        [
-          $this,
-          'matchConfigName',
-        ]
-      )));
+      $data = array_unique(array_merge($data, array_filter($active_names, [$this, 'matchConfigName'])));
     }
-
+  
     // Allow to delete the configuration if the split becomes inactive.
     return $data;
   }
+  
 
   /**
    * {@inheritdoc}