diff --git a/inc/admin-pages/class-hosting-integration-wizard-admin-page.php b/inc/admin-pages/class-hosting-integration-wizard-admin-page.php
index c84ba6993..f978c282f 100644
--- a/inc/admin-pages/class-hosting-integration-wizard-admin-page.php
+++ b/inc/admin-pages/class-hosting-integration-wizard-admin-page.php
@@ -367,4 +367,32 @@ public function section_test(): void {
 			]
 		);
 	}
+
+	/**
+	 * Register the script for the test page.
+	 *
+	 * @return void
+	 */
+	public function register_scripts() {
+		parent::register_scripts();
+
+		wp_enqueue_script(
+			'wu-integration-test',
+			wu_get_asset('integration-test.js', 'js'),
+			[
+				'jquery',
+				'wu-vue',
+			],
+			wu_get_version(),
+			true
+		);
+		wp_add_inline_script(
+			'wu-integration-test',
+			'var wu_integration_test_data = {
+				integration_id: "' . esc_js($this->integration->get_id()) . '",
+				waiting_message: "' . esc_js(__('Waiting for results...', 'ultimate-multisite')) . '"
+			};',
+			'before'
+		);
+	}
 }
diff --git a/inc/checkout/class-checkout-pages.php b/inc/checkout/class-checkout-pages.php
index d89b53463..a23c60b02 100644
--- a/inc/checkout/class-checkout-pages.php
+++ b/inc/checkout/class-checkout-pages.php
@@ -475,7 +475,12 @@ public function maybe_obfuscate_login_url(): void {
 
 			$wp_query->set_404();
 
-			include get_404_template();
+			$four_oh_four = get_404_template();
+
+			// Apparently not all themes have a 404 template.
+			if ($four_oh_four) {
+				include $four_oh_four;
+			}
 
 			die;
 		} else {
diff --git a/inc/installers/class-base-installer.php b/inc/installers/class-base-installer.php
index ad8863a00..f47a3eb3f 100644
--- a/inc/installers/class-base-installer.php
+++ b/inc/installers/class-base-installer.php
@@ -93,7 +93,7 @@ public function handle($status, $installer, $wizard) { // phpcs:ignore Generic.C
 		} catch (\Throwable $e) {
 			$wpdb->query('ROLLBACK'); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
 
-			return new \WP_Error(esc_html($installer), esc_html($e->getMessage()));
+			return new \WP_Error(esc_html($installer), wp_kses_post($e->getMessage()));
 		}
 
 		$wpdb->query('COMMIT'); // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
diff --git a/inc/integrations/host-providers/class-base-host-provider.php b/inc/integrations/host-providers/class-base-host-provider.php
index 300f1ff4f..22d9b40fd 100644
--- a/inc/integrations/host-providers/class-base-host-provider.php
+++ b/inc/integrations/host-providers/class-base-host-provider.php
@@ -81,7 +81,6 @@ public function init(): void {
 			 * Adds an admin notice telling the admin that they should probably enable this integration.
 			 */
 			$this->alert_provider_detected();
-			return;
 		}
 
 		/*
@@ -96,7 +95,6 @@ public function init(): void {
 				 * Adds an admin notice telling the admin that the provider is not correctly setup.
 				 */
 				$this->alert_provider_not_setup();
-				return;
 			}
 
 			/*
diff --git a/inc/models/class-domain.php b/inc/models/class-domain.php
index 1bde5da85..ce9ccf32d 100644
--- a/inc/models/class-domain.php
+++ b/inc/models/class-domain.php
@@ -452,7 +452,7 @@ public function has_valid_ssl_certificate() {
 	 *
 	 * @since 2.0.0
 	 *
-	 * @return bool
+	 * @return bool|\WP_Error
 	 */
 	public function save() {
 
@@ -473,8 +473,7 @@ public function save() {
 					 * Deprecated: Mercator created domain.
 					 *
 					 * @since 2.0.0
-					 * @param self The domain object after saving.
-					 * @param self The domain object before the changes.
+					 * @param self $domain The domain object after saving.
 					 * @return void.
 					 */
 					do_action_deprecated('mercator.mapping.created', $deprecated_args, '2.0.0', 'wu_domain_post_save');
@@ -489,8 +488,8 @@ public function save() {
 					 * Deprecated: Mercator updated domain.
 					 *
 					 * @since 2.0.0
-					 * @param self The domain object after saving.
-					 * @param self The domain object before the changes.
+					 * @param self $domain The domain object after saving.
+					 * @param self $before_changes The domain object before the changes.
 					 * @return void.
 					 */
 					do_action_deprecated('mercator.mapping.updated', $deprecated_args, '2.0.0', 'wu_domain_post_save');
diff --git a/views/wizards/host-integrations/test.php b/views/wizards/host-integrations/test.php
index 81d412847..7af497f76 100644
--- a/views/wizards/host-integrations/test.php
+++ b/views/wizards/host-integrations/test.php
@@ -77,15 +77,3 @@
 	</div>
 
 </div>
-
-<?php
-wp_enqueue_script('wu-integration-test', wu_get_asset('integration-test.js', 'js'), ['jquery', 'vue'], wu_get_version(), true);
-wp_add_inline_script(
-	'wu-integration-test',
-	'var wu_integration_test_data = {
-	integration_id: "' . esc_js($integration->get_id()) . '",
-	waiting_message: "' . esc_js(__('Waiting for results...', 'ultimate-multisite')) . '"
-};',
-	'before'
-);
-?>