[vpontis]

When a component unmounts, styled-jsx removes its <style> tag with tag.parentNode.removeChild(tag). If something else already took the tag out of the DOM (browser extensions, scrapers and screenshot tools that strip <style> tags), parentNode is null and this throws TypeError: Cannot read properties of null (reading 'removeChild'). The throw happens during React's commit phase, so the whole tree falls back to the nearest error boundary.

We see a few thousand of these a week in production, mostly from headless Chrome and some from real Chrome users with extensions.

This skips removal when the tag is already detached, in StyleSheet.deleteRule, StyleSheet.flush and StyleSheetRegistry.remove (server-rendered tags). The bookkeeping (_tags[index] = null, delete this._fromServer[styleId]) still runs, so the sheet stays consistent.

Added a test that detaches the tags before deleteRule and flush.