`gen-api-docs` command doesn't support non-array plugins

[nlucero]

Describe the bug

When the Docusaurus configuration file contains a plugins entry with at least one plugin defined in a non-array way (e.g. a function), the command docusaurus gen-api-docs <id> -p <plugin-id> stops working.

Expected behavior

docusaurus gen-api-docs <id> -p <plugin-id> should support plugins defined in other forms other than an array/tuple, as per the official documentation.

Current behavior

When running the gen-api-docs command with a plugin ID (-p argument), it tries to look it up in the plugins configuration entry in the Docusaurus configuration file (ref). The lookup function incorrectly assumes all elements in plugins are defined as arrays and a tries to read a plugin[1].id field, resulting in a TypeError: Cannot read properties of undefined (reading 'id') error if the plugin is not defined as an array/tuple (ref).

Possible solution

The getPluginConfig should guard against data[1] being undefined:

function getPluginConfig(plugins: any[], pluginId: string): any {
  return plugins.filter((data) => data[1]?.id === pluginId)[0][1];
}

Alternatively, since we only care about the docusaurus-plugin-openapi-docs instances, we could just call getPluginConfig here with the result of getPluginInstances (defined a few lines above):

const pluginConfig = getPluginConfig(pluginInstances, pluginId);

Steps to reproduce

1. Bootstrap a new Docusaurus application following the steps on the README of this repo
2. Edit plugins in docusaurus.config.ts, adding a non-array plugin to it. E.g.:

plugins: [
    ...,
    () => ({
      postBuild() {
        console.log('Build finished');
      },
    }),
  ],

3. Run docusaurus gen-api-docs {id} -p {pluginId} with valid IDs based on the config
4. The following error pop up in your console: OpenAPI docs plugin ID '{pluginId}' not found.

Screenshots

Context

Your Environment

Relevant dependencies:

"@docusaurus/core": "^3.8.1",
"@docusaurus/mdx-loader": "^3.8.1",
"@docusaurus/plugin-content-docs": "^3.8.1",
"@docusaurus/preset-classic": "^3.8.1",
"@docusaurus/theme-classic": "^3.8.1",
"@docusaurus/theme-common": "^3.8.1",
"docusaurus-plugin-openapi-docs": "^4.5.1",
"docusaurus-theme-openapi-docs": "^4.5.1",

Node@20.19.2

[letiescanciano]

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