You installed TypeScript 7, ran your build, and something broke. Maybe ESLint crashed with a cryptic TypeError: Cannot read properties of undefined (reading 'Cjs'). Maybe ts-jest stopped transforming your test files. Maybe your CI pipeline just went red for no reason you can point to.
You're not doing anything wrong.
TypeScript 7 shipped tsgo, a genuine Go port of the type-checker, not a rewrite from scratch. But the tools that plug into TypeScript don't talk to the type-checker directly, they talk to a programmatic API. That API isn't stable yet, it lands in 7.1. Until then, a chunk of the ecosystem throws errors the moment you point typescript at the new version.
The 10-second version
Don't replace typescript in your dependencies with the 7.x line if you use typescript-eslint, ts-jest, ts-morph, or any tool doing programmatic type-checking. Keep typescript pinned to 6.x for those tools, and install @typescript/native-preview alongside it purely for fast type-checking in CI or a manual tsgo --noEmit command. Two compilers, living side by side, each doing a different job.
