TypeError 'onSuccess' of undefined

[peterbe]

Is this a bug report?

Yes.

Did you try recovering your dependencies?

Not applicable.

Which terms did you search for in User Guide?

Making a Progressive Web App

Environment

  System:
    OS: macOS High Sierra 10.13.6
    CPU: x64 Intel(R) Core(TM) i7-7920HQ CPU @ 3.10GHz
  Binaries:
    Node: 10.11.0 - /usr/local/bin/node
    Yarn: 1.10.1 - /usr/local/bin/yarn
    npm: 6.4.1 - /usr/local/bin/npm
  Browsers:
    Chrome: 69.0.3497.100
    Safari: 12.0
  npmPackages:
    react: 16.5.2 => 16.5.2 
    react-dom: 16.5.2 => 16.5.2 
    react-scripts: 2.0.4 => 2.0.4 
  npmGlobalPackages:
    create-react-app: Not Found

The ^ output doesn't say but I'm on react-scripts 2.0.4 as you can see here:
https://github.com/peterbe/workon/blob/223dac8c62dda95c313bc57f6a9adc5362290a46/package.json#L29

Steps to Reproduce

1. Use Firefox Nightly (because that's the only way you can remove all previous service workers)
2. Visit https://workon.app/
3. First time it registers the service worker only you get this error:

Expected Behavior

Not get an error.

Actual Behavior

Reproducible Demo

Check out https://github.com/peterbe/workon/tree/223dac8c62dda95c313bc57f6a9adc5362290a46 and yarn install, yarn run build and serve -s build.

Or, if you have no previous service worker before open: https://workon.app

[peterbe]

Actually, I'm not sure I know how to reproduce this. Anyway...

The bug is that calling serviceWorker.register(); inside your src/index.js will eventually lead to the lines:

              // Execute callback
              if (config.onUpdate) {
                config.onUpdate(registration);
              }

But if config is undefined you get a TypeError:

[peterbe]

Solution is to either do serviceWorker.register({}); or changing the unsafe line to:

              // Execute callback
              if (config && config.onUpdate) {
                config.onUpdate(registration);
              }

[peterbe]

By the way, I applied the fix I mentioned in the PR by making this change so now it's no longer reproducible by visiting workon.app.