corrected settings name

composer.json

@@ -21,7 +21,5 @@
             "reference": "2.x"
         }
     ],
-    "require": {
-        "drupal/core": "^9"
-    }
+    "require": {   }
 }

modules/solr_site/src/Form/SolrsiteSettingsForm.php

@@ -23,7 +23,7 @@ class SolrsiteSettingsForm extends FormBase {
    * {@inheritdoc}
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
-    $config = \Drupal::config('roblib_search_solr.settings');
+    $config = \Drupal::config('roblib_search_solr_site.settings');
 
     $form['solr_site_url'] = array(
       '#type' => 'textfield',
@@ -59,7 +59,7 @@ class SolrsiteSettingsForm extends FormBase {
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
-    $config = \Drupal::configFactory()->getEditable('roblib_search_solr.settings');
+    $config = \Drupal::configFactory()->getEditable('roblib_search_solr_site.settings');
     $config->set('solr_site_url', $form_state->getValue('solr_site_url'))->save();
     $config->set('solr_site_num_results', $form_state->getValue('solr_site_num_results'))->save();
   }

modules/solr_site/src/Plugin/Block/RoblibSearchSolrsiteBestbet.php

@@ -19,7 +19,7 @@ class RoblibSearchSolrSiteBestbet extends BlockBase {
    * {@inheritdoc}
    */
  public function build() {
-    $search_url = \Drupal::config('roblib_search_solr.settings')
+    $search_url = \Drupal::config('roblib_search_solr_site.settings')
       ->get('solr_site_url');
     $settings = [
       'solr_site_search_url' => $search_url,

modules/solr_site/src/Plugin/Block/RoblibSearchSolrsiteGeneral.php

@@ -19,7 +19,7 @@ class RoblibSearchSolrsiteGeneral extends BlockBase {
    * {@inheritdoc}
    */
   public function build() {
-    $search_url = \Drupal::config('roblib_search_solr.settings')
+    $search_url = \Drupal::config('roblib_search_solr_site.settings')
       ->get('solr_site_url');
     $settings = [
       'solr_site_search_url' => $search_url,