diff --git a/core/includes/schema.inc b/core/includes/schema.inc
index cbbc6389b5..ce2217d055 100644
--- a/core/includes/schema.inc
+++ b/core/includes/schema.inc
@@ -76,13 +76,12 @@ function drupal_get_schema_versions($module) {
  *
  * @return string|int
  *   The currently installed schema version, or
- *   \Drupal\Core\Extension\SchemaInstallerInterface::UNINSTALLED if the module
- *   is not installed.
+ *   SchemaInstallerInterface::UNINSTALLED if the module is not installed.
  *
  * @deprecated in Drupal 8.8.0 and will be removed before Drupal 9.0.0. Use
- *   \Drupal\Core\Extension\SchemaInstallerInterface::getInstalledVersion()
- *   instead.
+ *   SchemaInstallerInterface::getInstalledVersion() instead.
  *
+ * @see Drupal\Core\Extension\SchemaInstallerInterface
  * @see https://www.drupal.org/node/2970993
  */
 function drupal_get_installed_schema_version($module, $reset = FALSE, $array = FALSE) {
@@ -99,9 +98,9 @@ function drupal_get_installed_schema_version($module, $reset = FALSE, $array = F
  *   The new schema version.
  *
  * @deprecated in Drupal 8.8.0 and will be removed before Drupal 9.0.0. Use
- *   \Drupal\Core\Extension\SchemaInstallerInterface::setInstalledVersion()
- *   instead.
+ *   SchemaInstallerInterface::setInstalledVersion() instead.
  *
+ * @see Drupal\Core\Extension\SchemaInstallerInterface
  * @see https://www.drupal.org/node/2970993
  */
 function drupal_set_installed_schema_version($module, $version) {
@@ -116,8 +115,9 @@ function drupal_set_installed_schema_version($module, $version) {
  *   The module for which the tables will be created.
  *
  * @deprecated in Drupal 8.8.0 and will be removed before Drupal 9.0.0. Use
- *   \Drupal\Core\Extension\SchemaInstallerInterface::install() instead.
+ *   SchemaInstallerInterface::install() instead.
  *
+ * @see \Drupal\Core\Extension\SchemaInstallerInterface
  * @see https://www.drupal.org/node/2970993
  */
 function drupal_install_schema($module) {
@@ -132,8 +132,9 @@ function drupal_install_schema($module) {
  *   The module for which the tables will be removed.
  *
  * @deprecated in Drupal 8.8.0 and will be removed before Drupal 9.0.0. Use
- *   \Drupal\Core\Extension\SchemaInstallerInterface::uninstall() instead.
+ *   SchemaInstallerInterface::uninstall() instead.
  *
+ * @see \Drupal\Core\Extension\SchemaInstallerInterface
  * @see https://www.drupal.org/node/2970993
  */
 function drupal_uninstall_schema($module) {
@@ -155,8 +156,9 @@ function drupal_uninstall_schema($module) {
  *   is returned.
  *
  * @deprecated in Drupal 8.8.0 and will be removed before Drupal 9.0.0. Use
- *   \Drupal\Core\Extension\SchemaInstallerInterface::getSchema() instead.
+ *   SchemaInstallerInterface::getSchema() instead.
  *
+ * @see \Drupal\Core\Extension\SchemaInstallerInterface
  * @see https://www.drupal.org/node/2970993
  */
 function drupal_get_module_schema($module, $table = NULL) {
diff --git a/core/lib/Drupal/Core/Extension/ModuleInstaller.php b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
index 8f3e0e6b3c..a472c84379 100644
--- a/core/lib/Drupal/Core/Extension/ModuleInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
@@ -67,7 +67,7 @@ class ModuleInstaller implements ModuleInstallerInterface {
    * @param \Drupal\Core\DrupalKernelInterface $kernel
    *   The drupal kernel.
    * @param \Drupal\Core\Extension\SchemaInstallerInterface|null $schema_installer
-   *   The schema installer service.
+   *   (optional) The schema installer service.
    *
    * @see \Drupal\Core\DrupalKernel
    * @see \Drupal\Core\CoreServiceProvider
@@ -77,6 +77,7 @@ public function __construct($root, ModuleHandlerInterface $module_handler, Drupa
     $this->moduleHandler = $module_handler;
     $this->kernel = $kernel;
     if (!$schema_installer) {
+      @trigger('Calling ModuleInstaller::constructor() with the $schema_installer argument is supported in Drupal 8.8.0 and will be required in Drupal 9.0.0.  See https://www.drupal.org/project/drupal/issues/2908886', E_USER_DEPRECATED);
       $schema_installer = \Drupal::service('schema_installer');
     }
     $this->schemaInstaller = $schema_installer;
diff --git a/core/lib/Drupal/Core/Extension/SchemaInstaller.php b/core/lib/Drupal/Core/Extension/SchemaInstaller.php
index 3acdf4b3cb..a66d52139f 100644
--- a/core/lib/Drupal/Core/Extension/SchemaInstaller.php
+++ b/core/lib/Drupal/Core/Extension/SchemaInstaller.php
@@ -185,7 +185,7 @@ public function getSchema($module, $table = NULL) {
    *   tables and fields to improve performance of serialize() and
    *   unserialize(). Defaults to TRUE.
    */
-  private function initialize(&$schema, $module, $remove_descriptions = TRUE) {
+  private function initialize(array &$schema, $module, $remove_descriptions = TRUE) {
     // Set the name and module key for all tables.
     foreach ($schema as $name => &$table) {
       if (empty($table['module'])) {