Informatics at FH Technikum Wien, after HTL Wien West. Vienna.

I mostly fix bugs in other people's code, usually in projects I've never opened before. Some of it has shipped with my name on it: jsdom 30.1.0, babel 8.0.5 and astro 7.2.4.

I do a lot of this with an AI coding agent, and I wrote down every way that went wrong. That became slop-free, a Claude Code skill for AI-assisted pull requests that maintainers actually want to merge.

Merged fixes. A lot of them started from the lists of known-broken tests that projects keep in their own repos.

node

• #66421: util.inspect raised the indent before reading a detached DataView's properties, the getter threw, and everything printed after it in the same call came out too far right. I found it while porting the same code to Deno.

prettier

• #19893, #19894, #19930, #19939: comments that moved every time you formatted, so the file never settled. In assignments, sequence expressions, parenthesized arrow chains and before satisfies/as. The last one took two rounds of review.
• #19908: code blocks inside md templates got a fence too short for their content.
• #19880: range formatting reached past the selection.
• #19849: escaped characters in markdown links.
• #19878: blockquote markers leaking into setext headings.

jsdom

• #4245: attributes kept pointing at their old document after a move. jsdom was missing the spec's steps for appending and replacing an attribute.
• #4246: getElementsByTagName kept lowercasing after its root moved into an XML document.
• #4244: setting the text of a <script> that was already in the document never ran it.

babel

• #18214: an optimisation merged a destructuring declaration with its emptiness check without looking at which variable the check was for, so const [{ a }, {}] = [x, y] lost a.

marked

• #4075: indentation after a hard line break got rendered. marked's own tests ignore whitespace, which is why nobody saw it.
• #4053: autolinks and inline links need different escaping under CommonMark.
• #4080: two spaces and a tab got treated as code.
• #4076: numeric character references like # weren't decoded.
• #4074: fenced code indented less than its fence kept too much indentation.
• #4073: an empty fence rendered a blank line.

fastify

• #7001: compileSerializationSchema passed null where the types and docs say undefined.

home-assistant/core

• #180532: a test stayed marked as expected-to-fail for months after its bug was fixed. pytest.xfail() stops before the assertion runs, so the test couldn't notice.

astro

• #17742: build.format: 'preserve' with trailingSlash: 'always' failed dynamic routes with Missing parameter.

supabase-js

• #2641: a failed passkey re-registration could delete a passkey that already worked.

• raspisentry: a Pi camera on a pan-tilt mount that follows your face and emails you a frame. OpenCV, with the camera and the dashboard in separate processes.
• downforce: the F1 standings as one long scroll, where the distance between teams is the points gap.
• dateideas: a date planner for two. The site is public, the data sits behind Firestore rules.
• press-it, swift-archive, nct-127: music archives that update themselves.
• SALURO: an anonymous payments prototype for school, Spring Boot and Docker. It's my diploma project, so the repo is private.

JavaScript, TypeScript, Node, Python, Java and Spring. English or German.

I take bug fix and debugging work. Send me the repo and a way to reproduce it: mck097@gmail.com