MV3: catch "Duplicate script ID 'inpage'" error (#15973)

* sw: catch Duplicate script ID 'inpage' error
- related to #15958

* typo: cased -> caused

app/scripts/app-init.js

@@ -132,7 +132,9 @@ chrome.runtime.onMessage.addListener(() => {
  * MAIN world injection does not work properly via manifest
  * https://bugs.chromium.org/p/chromium/issues/detail?id=634381
  */
-chrome.scripting.registerContentScripts([
+const registerInPageContentScript = async () => {
+  try {
+    await chrome.scripting.registerContentScripts([
       {
         id: 'inpage',
         matches: ['file://*/*', 'http://*/*', 'https://*/*'],
@@ -140,4 +142,17 @@ chrome.scripting.registerContentScripts([
         runAt: 'document_start',
         world: 'MAIN',
       },
-]);
+    ]);
+  } catch (err) {
+    /**
+     * An error occurs when app-init.js is reloaded. Attempts to avoid the duplicate script error:
+     * 1. registeringContentScripts inside runtime.onInstalled - This caused a race condition
+     *    in which the provider might not be loaded in time.
+     * 2. await chrome.scripting.getRegisteredContentScripts() to check for an existing
+     *    inpage script before registering - The provider is not loaded on time.
+     */
+    console.warn(`Dropped attempt to register inpage content script. ${err}`);
+  }
+};
+
+registerInPageContentScript();