Microsoft initially added Intellisense to Atom and called it VSCode. It was not great, but better than Atom.
Then VSCode got really good for an Electron-based app. It's still the quintessential Electron app, even if it trips over things like this now and again.
It's funny, because Electron was literally invented for Atom (note the wordplay!). I was a long-time holdout for Atom; I didn't want to ditch the original for the Microsoft takeover. But eventually I had no choice but to relent. Atom just got really sluggish once you had a few plugins running, and VSCode runs like a dream.
My speculation is that it had to do with the plugin architecture. Atom was very open-ended; writing a plug-in there, even an intellisense one, was more like writing a browser extension. Your code could just do whatever it wanted, including (easily) step on the toes of other code operating alongside it. You could literally have multiple different plugins implementing an intellisense UI, and then different language plugins would depend on different ones. And then they'd draw over each other, etc. VSCode on the other hand, a) includes lots of frameworks like a debugging UI and an intellisense UI out of the box so that there's a common standard, and b) exposes clean and clear APIs for common stuff, enabling extensions to be much more cooperative with each other and with the editor itself (which not only avoids conflicts, but improves performance too). It's like the iOS app philosophy vs the Android app philosophy.
Then VSCode got really good for an Electron-based app. It's still the quintessential Electron app, even if it trips over things like this now and again.