For increased type-safety, we can enable strictNullCheck selectively by overriding the global tsconfig file per directory.

"strictNullCheck" is the first flag that comes to my mind to enforce better type safety / quality, but other flags could be appropriate (e.g. "noImplicitAny", "noUnusedLocals" etc.) we need to check if it sounds reasonable to turn them on given the actual codebase.