fix: don't apply any locale-logic to non-existent routes (#1093)

If the resolved path for a given locale is 404 then return
resolved route based on the original path input rather than the
locale-adjusted path. This affects redirects on locale change, page
load, and the behavior of localePath and localeRoute APIs.

Avoids redirecting unnecessarily to a route that doesn't exist anyway.

That also fixes the security issue with redirecting to a different
domain but just in case added an additional measure against that.

Resolves #1092

src/templates/plugin.main.js

@@ -162,7 +162,7 @@ export default async (context) => {
       redirectPath = app.localePath(route.fullPath, locale)
     }
 
-    if (redirectPath === route.fullPath) {
+    if (!redirectPath || redirectPath === route.fullPath || redirectPath.startsWith('//')) {
       return ''
     }
 

src/templates/plugin.routing.js

@@ -52,15 +52,6 @@ function localeRoute (route, locale) {
   let localizedRoute = Object.assign({}, route)
 
   if (route.path && !route.name) {
-    const isDefaultLocale = locale === defaultLocale
-    // if route has a path defined but no name, resolve full route using the path
-    const isPrefixed =
-        // don't prefix default locale
-        !(isDefaultLocale && [STRATEGIES.PREFIX_EXCEPT_DEFAULT, STRATEGIES.PREFIX_AND_DEFAULT].includes(strategy)) &&
-        // no prefix for any language
-        !(strategy === STRATEGIES.NO_PREFIX) &&
-        // no prefix for different domains
-        !i18n.differentDomains
     const resolvedRoute = this.router.resolve(route.path).route
     const resolvedRouteName = this.getRouteBaseName(resolvedRoute)
     if (resolvedRouteName) {
@@ -71,6 +62,15 @@ function localeRoute (route, locale) {
         hash: resolvedRoute.hash
       }
     } else {
+      const isDefaultLocale = locale === defaultLocale
+      // if route has a path defined but no name, resolve full route using the path
+      const isPrefixed =
+          // don't prefix default locale
+          !(isDefaultLocale && [STRATEGIES.PREFIX_EXCEPT_DEFAULT, STRATEGIES.PREFIX_AND_DEFAULT].includes(strategy)) &&
+          // no prefix for any language
+          !(strategy === STRATEGIES.NO_PREFIX) &&
+          // no prefix for different domains
+          !i18n.differentDomains
       if (isPrefixed) {
         localizedRoute.path = `/${locale}${route.path}`
       }
@@ -89,7 +89,12 @@ function localeRoute (route, locale) {
     }
   }
 
-  return this.router.resolve(localizedRoute).route
+  const resolvedRoute = this.router.resolve(localizedRoute).route
+  if (resolvedRoute.name) {
+    return resolvedRoute
+  }
+  // If didn't resolve to an existing route then just return resolved route based on original input.
+  return this.router.resolve(route).route
 }
 
 function switchLocalePath (locale) {

test/browser.test.js

@@ -643,7 +643,7 @@ describe(`${browserString} (SPA)`, () => {
     page = await browser.newPage({ locale: 'fr' })
     await page.goto(url(path))
     expect(await (await page.$('body'))?.textContent()).toContain('page could not be found')
-    expect(await getRouteFullPath(page)).toBe(`/fr${path}`)
+    expect(await getRouteFullPath(page)).toBe(path)
   })
 })