#debugging 8 articles

• A parser branch whose entry condition accepts more than its collector loop consumes will freeze the tabgotchas / spfxA branch that accepts 1) but collects only 1. spins forever on one line until out-of-memory; one shared regex, a no-progress contract and an outer backstop, each sufficient alone
• Diagnostics that cannot survive the crash they are diagnosinggotchas / toolingFrozen threads stop repainting, sessionStorage dies with the tab and the next healthy run overwrites the crash report; persist synchronously and never gate recovery on a flag
• Load an SPFx bundle's lazy chunk from the browser console — no clicking through the UIgotchas / spfxPush a fake chunk with a runtime callback into the bundle's webpackJsonp_ array to get its real __webpack_require__, then req.e(chunkId) loads the chunk exactly as the app would — for checking 404s, SRI integrity or…
• Minified React error #310 (and friends) — the SPFx debugging cheatsheetgotchas / spfx#310/#300/#321/#31/#185 decoded for SPFx debugging
• Performance measurements taken in a hidden browser tab are worthless — and they look like a freezegotchas / toolingHidden tabs never fire requestAnimationFrame and clamp setTimeout to ~1/s, so the run times out and looks like the very freeze you were chasing (and the code under test never ran either); CSS transitions never advance…
• rules-of-hooks false-positive — a complex JSX && chain flags the wrong hookgotchas / spfxA complex conditional in your render blames the wrong hook; extract it to a const. Second trigger: sheer component size — there extracting conditions doesn't help, splitting the component does. Third trigger: the…
• SPFx MSGraphClient calls don't show in DevTools Network — and how to diagnose them anywaygotchas / graphSPFx Graph traffic invisible in Network; diagnose via performance entries, currentuser, DOM, user's response
• Two "Uncaught (in promise)" from sp-pages-assembly on a modern page are SharePoint's own, not your web partgotchas / spfxOn SharePoint Online modern pages the console can show two "Uncaught (in promise)" exceptions with reason undefined and a stack only inside sp-pages-assembly, on every load and on SPA navigation – they also appear on a…