fix(mdx): push last highlighted line when making highlight blocks

[nikolovlazar]

DESCRIBE YOUR PR

I noticed that in code blocks where the last line is highlighted it doesn't get shown. There's a good example in the TanStack Start React guide:

The code block ends abruptly and it doesn't show how to wrap the defaultStreamHandler with Sentry's wrapStreamHandlerWithSentry. I checked the mdx page and noticed that there's only one missing line from the code block and it's also the highlighted one.

The changes I made ensure that we "flush" any started highlight groups at the end before returning the markup. The previous implementation relied on having a non-highlighted line that follows a highlighted one in order to "flush" the group.

This PR would fix any code blocks that highlight the last line(s). I'm not sure if there are other instances other than the TanStack Start one.

After the fix:

Additionally, this PR removes the bottom padding of codeblocks whose last child is a highlight:

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[Copilot]

Pull Request Overview

This PR fixes the issue where the last highlighted line in MDX code blocks wasn’t being pushed into the rendered output.

• Added an index parameter to the reduce function
• Modified the conditional logic to flush highlighted groups when the last item is reached

Comments suppressed due to low confidence (1)

src/components/codeHighlights/codeHighlights.tsx:47

• Consider adding tests that specifically cover the case where the last line is highlighted to ensure that the flush logic handles this scenario as expected.

if (!isHighlightedLine || index === items.length - 1) {

[codecov]

Bundle Report

Changes will increase total bundle size by 280 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
sentry-docs-server-cjs	10.6MB	91 bytes (0.0%) ⬆️
sentry-docs-client-array-push	9.44MB	189 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: sentry-docs-server-cjs

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
1729.js	-3 bytes	1.58MB	-0.0%
../instrumentation.js	-3 bytes	911.63kB	-0.0%
9523.js	-3 bytes	887.68kB	-0.0%
../app/[[...path]]/page.js	100 bytes	538.95kB	0.02%

Files in ../app/[[...path]]/page.js:

• ./src/components/codeBlock/code-blocks.module.scss → Total Size: 300 bytes

App Routes Affected:

App Route	Size Change	Total Size	Change (%)
/[[...path]]	100 bytes	3.09MB	0.0%

view changes for bundle: sentry-docs-client-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
static/chunks/pages/_app-*.js	-3 bytes	868.67kB	-0.0%
static/css/*.css	95 bytes	18.64kB	0.51%
static/chunks/8931-*.js	-3 bytes	397.42kB	-0.0%
static/chunks/app/[[...path]]/page-*.js	100 bytes	77.85kB	0.13%
server/middleware-*.js	5.55kB	6.55kB	555.3% ⚠️
server/middleware-*.js	-5.55kB	1.0kB	-84.74%
static/VgjzlMgG-*.js (New)	77 bytes	77 bytes	100.0% 🚀
static/VgjzlMgG-*.js (New)	578 bytes	578 bytes	100.0% 🚀
static/5pkgtGrS5eCJ-*.js (Deleted)	-578 bytes	0 bytes	-100.0% 🗑️
static/5pkgtGrS5eCJ-*.js (Deleted)	-77 bytes	0 bytes	-100.0% 🗑️

Files in static/chunks/app/[[...path]]/page-*.js:

• ./src/components/codeBlock/code-blocks.module.scss → Total Size: 309 bytes

[Lms24]

Thanks for fixing this @nikolovlazar - great catch! (for context, I caused this in #12983)

I hope you don't mind but I'll merge this to get it out :)