Why is chrome.fileBrowserHandler API undefined when reading onExecute?

Question

Overview

I'm writing a ChromeOS Files extension for encrypting files. For that I'm using the Google Chrome chrome.fileBrowserHandler API. When opening the Files context menu, I get an "Encrypt" option (Open with… > Encrypt):

The issue I'm facing

The example code snipped provided by the API documentation does throw an Uncaught TypeError.

The error message written for accessibility:

// Warning: Service worker registration failed. Status code: 15
"service_worker": "background.js"

// Error: Uncaught TypeError: Cannot read properties of undefined (reading 'onExecute')
// Context
// background.js
// Stack Trace
// background.js:3 (anonymous function)
chrome.fileBrowserHandler.onExecute.addListener((id, details) => {

Why am I facing the error message?

Source Code

// background.js
"use strict";

chrome.fileBrowserHandler.onExecute.addListener((id, details) => {
  if (id === "encrypt") {
    chrome.windows.create({
      url: chrome.runtime.getURL('popup.html'),
      type: "popup"
    });
  }
});

// manifest.json
{
  "manifest_version": 3,
  "name": "Encrypt My Files",
  "description": "Encrypt files natively on ChromeOS",
  "version": "0.1.0",
  "permissions": ["fileBrowserHandler"],
  "background": {
    "service_worker": "background.js"
  },
  "action": {
    "default_popup": "popup.html"
  },
  "file_browser_handlers": [
    {
      "id": "encrypt",
      "default_title": "Encrypt",
      "file_filters": [
        "filesystem:*.*"
      ]
    }
  ],
  "minimum_chrome_version": "120"
}

Things I noticed

When specifying just a console.log statement in background.js, the extension can be turned on without any issues. Also, using a chrome.runtime.onInstalled.addListener in background.js (e.g. for context menus in web pages) works.