Handle semver issue in vue-router

[soletan]

• I confirm that this is an issue rather than a question.

Bug report

Steps to reproduce

1. Set up custom theme.
2. Use router exposed in enhanceApp.js for registering global navigation guard.
3. Implement redirection by invoking guard's next() handler with URL.
4. Run vuepress build.

Actual repro: https://github.com/soletan/vue-router-test

What is expected?

Build should succeed.

What is actually happening?

Build fails due to some pageMeta being undefined. In addition there are unhandled promise rejections logged as errors.

Other relevant information

Output of npx vuepress info in my VuePress project:

Environment Info:

  System:
    OS: Windows 10 10.0.19041
    CPU: (8) x64 Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz
  Binaries:
    Node: 12.16.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.4 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 6.14.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 85.0.4183.102
    Edge: Spartan (44.19041.423.0), Chromium (85.0.564.44)
  npmPackages:
    @vuepress/core:  1.5.4
    @vuepress/theme-default:  1.5.4
    vuepress: ^1.5.4 => 1.5.4
  npmGlobalPackages:
    vuepress: Not Found

• My analysis: https://stackoverflow.com/questions/63351479/vuepress-build-docs-get-referenceerror-pagemeta-is-not-defined
• some related issue in vue-router: Error: Redirected from X to Y via a navigation guard. vue-router#3221
• the actual change: vuejs/vue-router@4c727f9#diff-feafce5e816936212eccd6808c5421a6R176
• working fix: downgrading vue-router to 3.1.6 explicitly by using ~3.1.3 instead of ^3.1.3 in your dependencies

[soletan]

Since I was kind of asked for this by vue-router, here is a test project for reproduction:

https://github.com/soletan/vue-router-test

Steps to reproduce

1. git checkout 0c5d
2. yarn install --frozen-lockfile
3. npm run build --> fails
4. git checkout HEAD
5. yarn install -frozen-lockfile
6. npm run build --> succeeds

In 4 and 5 vuepress is forced to use vue-router 3.1.6 instead of 3.4.3 matching its selector ^3.1.3. Since everything is kept as before the only thing changing is vue-router library.

[soletan]

Okay, this issue is a total blocker ... built website doesn't work due to having unhandled promise rejections. Two weeks of working on an attempt to have a website built with Vuepress is currently wasted. A popup meant to appear on certain conditions only keeps appearing each and every time the built site is opened, even though poorman's debugging is revealing that every condition in a v-if is meant to hide that popup, but in build's SSR something is causing it to be revealed and there is no app fully taking over control after the HTML has been loaded into browser for I can't even click on a button of that popup. When I try to prevent popup from being revealed in SSR it won't show up at runtime in browser either. FWIW this SSR feature is broken right now.

Everything is working fine in dev mode. So I don't know what Vuepress is doing here. I can't dive into another application just to find out what is going on. The demonstration provided in my previous comment is pretty simple. So please, could someone with proper skills in developing VuePress have a look into this issue and tell me what is causing those rejections? Why is vuepress having issues with properly integrating vue-router? Why are you exposing router as part of a custom theme's setup function if it isn't fully usable. Just a short note in documentation would help ...

Haven't been this much frustrated with regards to Vue.js and its ecosystem for years now.