fix(analytics): drop browser-extension exceptions in before_send

[posthog]

Changes

Problem

• A browser extension (Dark Reader) makes error tracking open a fresh issue for every page a visitor loads — pure triage cost, no site defect. The fingerprint keys off the page URL, so each new URL mints a new issue nobody can fix.
• The extension injects an inline script. When it throws, its one frame is global code at line 1 of the document URL and is marked in_app, so the event reads as a first-party site error.
• before_send did not catch this shape. #19599 does not cover it either: its rule drops exceptions with no in_app frame, and this frame has in_app set.

Fix — extend the single before_send hook (gatsby/onPreBootstrap.ts), stacked on #19599:

Exception shape	Action	Reason
only frame is global code at line 1 of the document URL	drop	inline script injected by an extension; the site cannot fix it
any other single or multi frame	keep	real product errors load from separate script files, never inline

Our own code loads from separate .js files, so a frame whose filename is the page's own document URL is always injected script.

Agent context

• Observed as ReferenceError: Can't find variable: DarkReader on iOS Safari. DarkReader exists nowhere in this repo. A sibling variant (Can't find variable: __firefox__) has the same shape and is dropped by the same rule.
• Stacked on fix(analytics): drop unactionable client-side exceptions in before_send #19599 to avoid a conflict in the same hook; base this branch on that PR's branch.

Checklist

• I've read the docs and/or content style guides.
• Words are spelled using American English
• Use relative URLs for internal links
• I've checked the pages added or changed in the Vercel preview build
• If I moved a page, I added a redirect in vercel.json

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[posthog]

🦔 PostHog Review reviewed this pull request

Found 1 must fix, 0 should fix, 0 consider.

Published 1 finding (view the review).

Resolved comments: 1 fixed

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Aug 29, 2026 02:21AM

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[posthog]

PostHog Review

Found 1 must fix.

[github-actions]

Bundle report

Total JS (gzip)

8.15 MiB (+0.7 KiB / +0.0%)

Eager graph (modules shipped in each entrypoint's initial chunks)

Entrypoint	Eager size	Budget	Modules
✅ app	16.91 MiB (no change)	report-only	2036

Largest modules in the app closure

Module	Size
./src/data/mcp-tools.json	1053.9 KiB
css ./node_modules/.pnpm/css-loader@5.2.7_webpack@5.101.3/node_modules/css-loader/dist/cjs.js??ruleSet[1].rules[8].oneOf[1].use[1]!./node_modules/.pnpm/postcss-loader@4.3.0_postcss@8.5.6_webpack@5.101.3/node_modules/postcss-loader/dist/cjs.js??ruleSet[1].rules[8].oneOf[1].use[2]!./src/styles/global.css	754.5 KiB
./src/components/Stickers/Stickers.tsx	696.4 KiB
./node_modules/.pnpm/@radix-ui+react-icons@1.3.2_react@18.3.1/node_modules/@radix-ui/react-icons/dist/react-icons.esm.js	481.4 KiB
./node_modules/.pnpm/rehype-raw@7.0.0/node_modules/rehype-raw/lib/index.js + 29 modules	395.1 KiB
./src/hooks/useCustomers.tsx + 55 modules	370.0 KiB
./node_modules/.pnpm/@posthog+icons@0.36.6_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.es.js	354.8 KiB
./node_modules/.pnpm/react-markdown@8.0.7_@types+react@16.14.66_react@18.3.1/node_modules/react-markdown/lib/react-markdown.js + 88 modules	351.4 KiB
./src/components/ProductComparisonTable/index.tsx + 126 modules	301.7 KiB
./node_modules/.pnpm/cloudinary-core@2.14.0_lodash@4.17.21/node_modules/cloudinary-core/cloudinary-core.js	281.9 KiB
./src/components/SearchUI/index.tsx + 87 modules	273.0 KiB
./node_modules/.pnpm/@posthog+brand@0.8.0_react@18.3.1/node_modules/@posthog/brand/dist/generated/hoggies/svg/magnifying-glass.mjs	254.7 KiB
./node_modules/.pnpm/framer-motion@10.18.0_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/framer-motion/dist/es/render/dom/motion.mjs + 109 modules	253.9 KiB
./node_modules/.pnpm/d3@7.9.0/node_modules/d3/src/index.js + 208 modules	247.4 KiB
./src/components/Pricing/PricingSlider/Slider.tsx + 87 modules	240.1 KiB

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Eager-graph budgets are report-only until a baseline is established. Sizes are gzip of public/**/*.js; eager size is webpack module source bytes for the modules actually shipped in the entrypoint's initial chunks (post-tree-shake).