build: fix TypeError in prism-eslint-hooks.js

[fasttime]

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What is the purpose of this pull request? (put an "X" next to an item)

[X] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofix to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

What changes did you make? (Give an overview)

This PR fixes an issue in the docs build process that is causing some incorrect rule examples in the indent and indent-legacy rules to be displayed without red markers for errors, for example here.

This is due to a TypeError that occurs because of an incorrect condition in another part of the code. This incorrect condition allows the creation of an array with an undefined element where only strings or plain objects are expected as elements:

js TypeError: Cannot read properties of undefined (reading 'content')
    at getTokenContent (/Users/noone/GitHub/eslint/eslint/docs/tools/prism-eslint-hook.js:189:30)
    at splitTokensByLineFeed (/Users/noone/GitHub/eslint/eslint/docs/tools/prism-eslint-hook.js:309:33)
    at splitTokensByLineFeed.next (<anonymous>)
    at splitTokensByLineFeed (/Users/noone/GitHub/eslint/eslint/docs/tools/prism-eslint-hook.js:321:41)
    at splitTokensByLineFeed.next (<anonymous>)
    at splitTokensByLineFeed (/Users/noone/GitHub/eslint/eslint/docs/tools/prism-eslint-hook.js:321:41)
    at splitTokensByLineFeed.next (<anonymous>)
    at convertMarked (/Users/noone/GitHub/eslint/eslint/docs/tools/prism-eslint-hook.js:392:24)
    at convertMarked.next (<anonymous>)
    at /Users/noone/GitHub/eslint/eslint/docs/tools/prism-eslint-hook.js:402:30

The error is visibile in the Netlify logs under Deploy log > Building > Lines 219-306 (last production deploy: https://app.netlify.com/sites/docs-eslint/deploys/65f345a38ee0750008f1a05c#L219-L306) or when manually running npm run build in the docs folder.

Is there anything you'd like reviewers to focus on?

There are no unit tests for prism-eslint-hooks.js. Shall we add one?

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[mdjermanovic]

According to Prism typings, token.content can be a string, Token, or array of strings/Tokens, so it looks like this was targeting the Token case, but missed the fact that token itself can be a string, and that's causing the crash?

Would it make sense to keep this condition and fix the problem this way:

for (const token of tokens) {

+    if (typeof token === "string") {
+        yield token;
+        continue;
+   }

    const content = getTokenContent(token);

[fasttime]

The condition is flawed because Array.isArray(token.content) implies typeof token.content !== "string", but I think it's a good idea to check if token is a string early in the loop nonetheless, because it makes the logic easier to follow. In the below condition it's enough to check that token.content is not a string to verify that it's an array. I wasn't able to reproduce the case where token.content is a Token, but in theory, it should work as well.

[ota-meshi]

LGTM! Thank you for fixing the problem!

[mdjermanovic]

LGTM, thanks!