Enable @typescript-eslint/no-unnecessary-condition in the repo

And resolve offending sites.

First, locate the ESLint configuration file (likely .eslintrc or similar) to enable the @typescript-eslint/no-unnecessary-condition rule. Then run the linter to identify all offending code sites across the TypeScript codebase. Review each flagged location to determine if the condition is truly unnecessary and safely remove or adjust it, ensuring no regressions. Testing changes by running the project's test suite is essential to verify correctness.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.