avoid calling listener when provider is not defined

pages/alert/runtime-content.page.tsx

@@ -1,7 +1,7 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-import React, { useContext, useState } from 'react';
+import React, { useContext, useMemo, useState } from 'react';
 import { render, unmountComponentAtNode } from 'react-dom';
 
 import {
@@ -72,7 +72,7 @@ export default function () {
   const [unrelatedState, setUnrelatedState] = useState(false);
   const [contentSwapped, setContentSwapped] = useState(false);
 
-  const content1 = loading ? <Box>Loading...</Box> : <Box>Content</Box>;
+  const content1 = useMemo(() => (loading ? <Box>Loading...</Box> : <Box>Content</Box>), [loading]);
   const content2 = loading ? <Box>Loading...</Box> : <Box>There was an error: Access denied because of XYZ</Box>;
 
   return (

src/internal/plugins/controllers/alert-flash-content.ts

@@ -35,7 +35,7 @@ export interface AlertFlashContentConfig {
   runReplacer: (context: AlertFlashContentContext, replacementApi: ReplacementApi) => AlertFlashContentResult;
 }
 
-export type AlertFlashContentRegistrationListener = (provider?: AlertFlashContentConfig) => void | (() => void);
+export type AlertFlashContentRegistrationListener = (provider: AlertFlashContentConfig) => () => void;
 
 export interface AlertFlashContentApiPublic {
   registerContentReplacer(config: AlertFlashContentConfig): void;
@@ -48,14 +48,16 @@ export interface AlertFlashContentApiInternal {
 
 export class AlertFlashContentController {
   #listeners: Array<AlertFlashContentRegistrationListener> = [];
-  #cleanups = new Map<AlertFlashContentRegistrationListener, null | (() => void)>();
+  #cleanups = new Map<AlertFlashContentRegistrationListener, () => void>();
   #provider?: AlertFlashContentConfig;
 
   #scheduleUpdate = debounce(
     () =>
       this.#listeners.forEach(listener => {
-        const cleanup = listener(this.#provider) ?? null;
-        this.#cleanups.set(listener, cleanup);
+        if (this.#provider) {
+          const cleanup = listener(this.#provider);
+          this.#cleanups.set(listener, cleanup);
+        }
       }),
     0
   );
@@ -78,12 +80,13 @@ export class AlertFlashContentController {
   };
 
   onContentRegistered = (listener: AlertFlashContentRegistrationListener) => {
-    const cleanup = listener(this.#provider);
-    this.#listeners.push(listener);
-    if (cleanup) {
+    if (this.#provider) {
+      const cleanup = listener(this.#provider);
+      this.#listeners.push(listener);
       this.#cleanups.set(listener, cleanup);
+    } else {
+      this.#listeners.push(listener);
     }
-
     return () => {
       this.#cleanups.get(listener)?.();
       this.#listeners = this.#listeners.filter(item => item !== listener);

src/internal/plugins/helpers/use-discovered-content.tsx

@@ -45,7 +45,7 @@ export function createUseDiscoveredContent(
           return true;
         }
 
-        mountedProvider.current = provider?.runReplacer(context, {
+        mountedProvider.current = provider.runReplacer(context, {
           hideHeader() {
             if (checkMounted('hideHeader')) {
               setFoundHeaderReplacement('remove');