feat: enhance error message when plugin module isn't loaded correctly

[pburdette]

Fix for #4024

@sodatea Let me know if it makes more sense to implement this change somewhere else in the codebase.

[haoqunjiang]

Thanks for this PR! But the error actually comes from here:

vue-cli/packages/@vue/cli/lib/add.js

Lines 51 to 55 in 80e5d7f

	invoke.runGenerator(context, {
	id: 'core:router',
	apply: loadModule('@vue/cli-service/generator/router', context),
	options
	})

For normal plugins, we do have proper error handling:

vue-cli/packages/@vue/cli/lib/invoke.js

Lines 72 to 83 in 80e5d7f

	const id = findPlugin(pkg.devDependencies) || findPlugin(pkg.dependencies)
	if (!id) {
	throw new Error(
	`Cannot resolve plugin ${chalk.yellow(pluginName)} from package.json. ` +
	`Did you forget to install it?`
	)
	}
	const pluginGenerator = loadModule(`${id}/generator`, context)
	if (!pluginGenerator) {
	throw new Error(`Plugin ${id} does not have a generator.`)
	}

So once this issue is resolved and vuex & vue-router become standalone plugins, the error message will be correctly displayed. I think @pksunkara is currently working on this.

[pksunkara]

I just implemented the first part of it, PR #4196

[pburdette]

@sodatea ahh makes sense now. This sounds like a more permanent fix. Is there a way I can get in touch to find out what issues to work on? I plan on dedicating some time to knock out some smaller issues. Thanks

[haoqunjiang]

@beardedpayton @pksunkara

Just wrote up a Status of Vue CLI
Thanks for all your kind help 😀