Chrome Extention not Running Code onClick

Question

I am trying to make a bookmarklet to Chrome extension converter that makes MV3 extensions. I cant get the extension to run the code when clicked. It just gives the default popup for extensions.

This is the relevant part of my code:

json = """
{
  "name": "%s",
  "description": "%s",
  "version": "1.0",
  "manifest_version": 3,
  "minimum_chrome_version": "120",
  "background": {
    "serviceworker": "main.js"
  },
  "permissions": [
    "userScripts", 
    "activeTab"
  ],
  "host_permissions": [
    "*://*/*"
  ]
}
""" % ( name, description)
mainjs = """
chrome.action.onClicked.addListener((tab) => {
target: {tabId: tab.id},
async chrome.userScripts.register({
    id: 'bookmarklet',
    matches: ['*://*/*'],
    js: [{ file: 'user-script.js' }]
  });
});
"""
with open('manifest.json', 'w') as manifest:
    manifest.write(json)
with open('main.js', 'w') as main:
    main.write(mainjs)
with open('user-script.js', 'w') as us:
    us.write(code)

I've tried changing various parts of mainjs but nothing has worked.