Catch all route with prefix throw Expected "0" to be defined

[manniL]

Version

3.0.2

Reproduction link

https://codesandbox.io/s/lykxn57kr7

Prefix routes are fine when they don't have a prefix but with a /sth/ it becomes problematic.

This causes problems especially for nuxt-i18n together with a catch-all-route (as it uses lang prefixes)

Steps to reproduce

1. Visit the CSB/Website
2. See warning in the console.

Info: This did not happen in 3.0.1
Related: #2496, #2503

What is expected?

No warning

What is actually happening?

Warning

[manniL]

Update: @clarkdo fixed that in Nuxt via https://github.com/nuxt/nuxt.js/pull/4394/files#diff-90f8231837497e514ba4e8e477131204R437

Maybe we could apply the same fix (as the original part is still in the code as is https://github.com/nuxt/nuxt.js/pull/4394/files) or revert the change? ☺️

[posva]

I think it's better to modify the check done to display the warning 😆

[manniL]

@posva Well,

vue-router/dist/vue-router.js

Line 828 in cf9dc11

throw new TypeError('Expected "' + token.name + '" to be defined')

is part of the pathToRegexp package.

Related src file:

vue-router/src/util/params.js

Lines 1 to 27 in deba65a

	/* @flow */
	import { warn } from './warn'
	import Regexp from 'path-to-regexp'
	// $flow-disable-line
	const regexpCompileCache: {
	[key: string]: Function
	} = Object.create(null)
	export function fillParams (
	path: string,
	params: ?Object,
	routeMsg: string
	): string {
	try {
	const filler =
	regexpCompileCache[path] ||
	(regexpCompileCache[path] = Regexp.compile(path))
	return filler(params || {}, { pretty: true })
	} catch (e) {
	if (process.env.NODE_ENV !== 'production') {
	warn(false, `missing param for ${routeMsg}: ${e.message}`)
	}
	return ''
	}
	}

[posva]

I mean we should be able to do it in the warning check. I haven't checked it at runtime, but I'm talking about util/params.js

[rchl]

This bug triggers when calling router.resolve() with params: {pathMatch: 'foo'} when matching against existing routes that have * wildcard. That makes me wonder what will happen if we are trying to resolve with params: {pathMatch: 'foo'} and there is actual route that defines param called pathMatch. It would then match, which would likely be incorrect. It might be a bit of a stretch but...

I wonder if the special case of 'unnamed' param might need a more tailored approach here.

[rchl]

(BTW. This bug is a recent regression related to pathMatch stuff so I would consider it more than just an 'improvement'. It means that with perfectly valid setup, one can now get warnings when matching routes.)