Reset pre chat values on save to make sure the keys are in sequential order.

Reset the pre-chat field configuration keys on save by calling array_values. Since we're resetting the keys on save, we no longer have to / can call array_values on the adding of fields.

Closes #3524814

src/Plugin/Block/SalesforceMfw.php

@@ -223,7 +223,8 @@ class SalesforceMfw extends BlockBase implements ContainerFactoryPluginInterface
     $this->configuration['utility_bootstrap'] = $form_state->getValue('utility_bootstrap');
     $this->configuration['language'] = $form_state->getValue('language');
     $this->configuration['allow_token_replacement'] = $form_state->getValue('allow_token_replacement');
-    $this->configuration['prechat_fields'] = $form_state->getValue(['fields_container', 'prechat_fields']) ?: [];
+    $prechat_fields = $form_state->getValue(['fields_container', 'prechat_fields']);
+    $this->configuration['prechat_fields'] = is_array($prechat_fields) ? array_values($prechat_fields) : [];
 
     parent::submitConfigurationForm($form, $form_state);
   }
@@ -279,7 +280,7 @@ class SalesforceMfw extends BlockBase implements ContainerFactoryPluginInterface
     ];
 
     // Update the form state with the modified fields.
-    $form_state->set('prechat_fields', array_values($fields));
+    $form_state->set('prechat_fields', $fields);
 
     // Rebuild the form to reflect the updated fields.
     $form_state->setRebuild(TRUE);