Cannot set path option in config.js

[x] I confirm that this is an issue rather than a question.

Bug report

Steps to reproduce

[x] I prepared a reproduction repo, here is the reproduction repo:

https://github.com/ijdickinson/vuepress-theme-blog-bug

[ ] This issue doesn't need a reproduction repro, here is the steps to reproduce

What is expected?

The only change to the setup created by yarn create vuepress is that I added a directories option to the config.js, to change the path to /posts/.

I expected that yarn build should succeed

What is actually happening?

Build error message:

ian@alder $ yarn build
yarn run v1.22.10
$ vuepress build blog
wait Extracting site metadata...
tip Apply theme @vuepress/theme-blog ...
warning directories.filter is not a function
tip Apply plugin container (i.e. "vuepress-plugin-container") ...
tip Apply plugin @vuepress/register-components (i.e. "@vuepress/plugin-register-components") ...
tip Apply plugin @vuepress/nprogress (i.e. "@vuepress/plugin-nprogress") ...
tip Apply plugin @vuepress/medium-zoom (i.e. "@vuepress/plugin-medium-zoom") ...
tip Apply plugin @vuepress/search (i.e. "@vuepress/plugin-search") ...

✔ Client
  Compiled successfully in 7.96s

✔ Server
  Compiled successfully in 4.90s

wait Rendering static HTML...
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
[Vue warn]: Error in render: "TypeError: Cannot read property 'feed' of undefined"

found in

---> <Feed>
       <Header>
         <Anonymous>
           <Root>
error Error rendering /404.html: false
undefined
error Error rendering /_posts/2018-11-7-frontmatter-in-vuepress-3.html: false
undefined
error Error rendering /_posts/2019-2-26-markdown-slot-2.html: false
undefined
error Error rendering /_posts/2018-11-7-frontmatter-in-vuepress-2.html: false
undefined
error Error rendering /_posts/2019-2-26-markdown-slot-4.html: false
undefined
error Error rendering /_posts/2019-2-26-markdown-slot.html: false
undefined
error Error rendering /_posts/2019-2-26-markdown-slot-3.html: false
undefined
error Error rendering /_posts/2019-5-6-writing-a-vuepress-theme-2.html: false
undefined
error Error rendering /_posts/2018-11-7-frontmatter-in-vuepress.html: false
undefined
error Error rendering /_posts/2019-5-6-writing-a-vuepress-theme-3.html: false
undefined
error Error rendering /_posts/2019-5-6-writing-a-vuepress-theme-4.html: false
undefined
error Error rendering /_posts/2019-5-6-writing-a-vuepress-theme.html: false
undefined
TypeError: Cannot read property 'feed' of undefined
    at Proxy.firstEnabledFeed (node_modules/@vuepress/theme-blog/components/Feed.vue:15:0)
    at Proxy.computedGetter (/home/ian/projects/personal/test-blog/node_modules/vue/dist/vue.runtime.common.dev.js:4831:15)
    at Proxy.Feedvue_type_template_id_07295367_render (node_modules/@vuepress/theme-blog/components/Feed.vue?3af9:1:89)
    at VueComponent.Vue._render (/home/ian/projects/personal/test-blog/node_modules/vue/dist/vue.runtime.common.dev.js:3538:22)
    at resolve (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8415:27)
    at waitForServerPrefetch (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8287:3)
    at renderComponentInner (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8426:3)
    at renderComponent (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8383:5)
    at RenderContext.renderNode (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8294:5)
    at RenderContext.next (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:2598:23)
    at cachedWrite (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:2451:9)
    at renderStringNode$1 (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8501:5)
    at RenderContext.renderNode (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:8292:5)
    at RenderContext.next (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:2598:23)
    at RenderContext.cachedWrite [as write] (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:2451:9)
    at RenderContext.next (/home/ian/projects/personal/test-blog/node_modules/vue-server-renderer/build.dev.js:2602:25)
error Command failed with exit code 1.

Other relevant information

npx vuepress info:

ian@alder $ npx vuepress info

Environment Info:

  System:
    OS: Linux 5.8 Ubuntu 20.10 (Groovy Gorilla)
    CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
  Binaries:
    Node: 12.18.2 - ~/.nvm/versions/node/v12.18.2/bin/node
    Yarn: 1.22.10 - ~/.nvm/versions/node/v12.18.2/bin/yarn
    npm: 7.8.0 - ~/.nvm/versions/node/v12.18.2/bin/npm
  Browsers:
    Chrome: Not Found
    Firefox: 87.0
  npmPackages:
    @vuepress/core:  1.8.2 
    @vuepress/theme-default:  1.8.2 
    vuepress: ^1.3.1 => 1.8.2 
  npmGlobalPackages:
    vuepress: Not Found

vuepress / vuepress-theme-blog

Cannot set path option in config.js #118

Bug report

Steps to reproduce

What is expected?

What is actually happening?

Other relevant information