Custom routes trigger broken links on build

🐛 Bug Report

Prerequisites

• I’m using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io
• I have read the console error message carefully (if applicable)

Description

I have a custom plugin that adds /api/* routes through actions.addRoute(). This whole flow works great. You can see the code here: https://github.com/milesj/docusaurus-plugin-typedoc-api/blob/master/packages/plugin/src/index.ts#L208

However, when running yarn build, all the /api/* routes fail on broken links, like so:

- On source page path = /api/pipeline/class/Context:
   -> linking to /api
   -> linking to /blog

- On source page path = /api/pipeline/class/Monitor:
   -> linking to /api
   -> linking to /blog

- On source page path = /api/pipeline/class/ParallelPipeline:
   -> linking to /api
   -> linking to /blog

- On source page path = /api/pipeline/class/PooledPipeline:
   -> linking to /api
   -> linking to /blog

- On source page path = /api/pipeline/class/Routine:
   -> linking to /api
   -> linking to /blog

- On source page path = /docs/tutorial-extras/manage-docs-versions:
   -> linking to /api
   -> linking to /blog

- On source page path = /docs/tutorial-extras/translate-your-site:
   -> linking to /api
   -> linking to /blog

I’m not sure how to resolve this or if this is just an oversight.

The routes do appear in the .docusaurus/routes.js file, but not sure if that matters.

Have you read the Contributing Guidelines on issues?

Yes

Steps to reproduce

Use https://new.docusaurus.io to create a CodeSandbox reproducible demo of the bug.

Creating a sandbox of this is too complicated. There are 2 ways to verify this though:

1. Clone and checkout this PR which attempts to integrate and test the plugin: https://github.com/milesj/boost/pull/157

git clone [e-mail]:milesj/boost.git
cd boost
git checkout typedoc
yarn install && yarn run build
cd website
yarn run build

1. Install the docusaurus-plugin-typedoc-api package and install it in a project: https://www.npmjs.com/package/docusaurus-plugin-typedoc-api

Expected behavior

The broken links check doesn’t fail on custom routes.

Actual behavior

The broken links check fails on custom routes.

I can bypass it for now by changing the onBrokenLinks setting but this isn’t ideal.

Your environment

• Public source code: https://github.com/milesj/boost/pull/157
• Public site URL: N/A
• Docusaurus version used: 2.0.0-beta.4
• Environment name and version (e.g. Chrome 78.0.3904.108, Node.js 10.17.0): Any node/yarn version
• Operating system and version (e.g. Ubuntu 20.04.2 LTS): MacOS/Ubuntu

[milesj]

Got it working, thanks for checking.

I have some other things to discuss but I’ll create new issues for them.

[slorber]

great, looks like it also fixed the 404 issue on https://boostlib.dev/api 👍