Service Worker required when disabled in dev

[tysonmatanich]

What is the current behaviour?
When running preact watch --sw false it still tries to attach a service worker. preact watch works fine which should default sw to false (https://github.com/preactjs/preact-cli#preact-watch).

Steps to Reproduce

1. Use a project without a .\src\sw.js
2. Run preact watch --sw false
3. See error

Build failed!

× ERROR Entry module not found: Error: Can't resolve '.\src\sw.js' in '.\src'
× ERROR InjectManifest: Entry module not found: Error: Can't resolve '.\src\sw.js' in '.\src'

What is the expected behaviour?
Build should succeed using same behavior as preact watch which defaults sw to false

Please mention any other relevant information
I'm assuming it was introduced in 9f9277b

Environment Info:

System:
OS: Windows 10 10.0.19043
Binaries:
Node: 14.16.1 - C:\Program Files\nodejs\node.EXE
npm: 6.14.12 - C:\Program Files\nodejs\npm.CMD
Browsers:
Edge: Spartan (44.19041.1023.0), Chromium (93.0.961.47)
npmPackages:
preact: ^10.5.14 => 10.5.14
preact-cli: ^3.2.2 => 3.2.2
preact-render-to-string: ^5.1.19 => 5.1.19
preact-router: ^3.2.1 => 3.2.1

[developit]

any chance this works correctly via preact watch --no-sw?

[tysonmatanich]

Yes it does

✅ preact watch
✅ preact watch --no-sw
❌preact watch --sw false

[rschristian]

preact-cli/packages/cli/lib/lib/webpack/webpack-client-config.js

Line 41 in b3b6984

if (env.sw) {

Looks like we're not converting the "false" into a boolean in watch mode as we do in build, just passing the string value through.

Will try to get a fix together here.

[tysonmatanich]

It also seems the changes in 9f9277b broke the workaround in #955 (comment) for using a ServiceWorker in watch mode.

[rschristian]

@tysonmatanich What doesn't seem to be working? That workaround, as far as I can tell, just matches what's already provided.

That exact config should be broken, as using it will result in duplicate plugins being pushed.

[tysonmatanich]

The workaround allows for the custom serviceworker to be used when running with preact watch --sw, hence the if(env.isWatch)

[rschristian]

Sorry, I don't understand. You can customize the config as-is:

export default {
    /**
     * Function that mutates the original webpack config.
     * Supports asynchronous changes when a promise is returned (or it's an async function).
     *
     * @param {object} config - original webpack config.
     * @param {object} env - options passed to the CLI.
     * @param {WebpackConfigHelpers} helpers - object with useful helpers for working with the webpack config.
     **/
    webpack(config, env, helpers) {
        if (env.isWatch) {
            const manifestPlugin = helpers.getPluginsByName(config, 'InjectManifest')[0];
            // You can make any modifications you'd like to the manifestPlugin here
        }    
    }
};