chore: improve kando maintenance path

[quyentonndbs]

Summary:

• Add or tighten focused edge-case tests or type assertions in src/main/index.ts, test/math.spec.ts related to TypeScript, frontend tooling, test stability, build fixes; avoid docs-only changes and broad refactors.
• Keep the change narrow so it is straightforward to review.

Notes:

• I kept this scoped to the relevant implementation and tests.

[Schneegans]

Hi there! Why do you think that especially this is necessary? It looks like a very random change. Did you encounter a specific issue during usage of Kando which made you consider these changes?