Refactor to enforce strictNullChecks

This commit applies `strictNullChecks` to the entire codebase to improve
maintainability and type safety. Key changes include:

- Remove some explicit null-checks where unnecessary.
- Add necessary null-checks.
- Refactor static factory functions for a more functional approach.
- Improve some test names and contexts for better debugging.
- Add unit tests for any additional logic introduced.
- Refactor `createPositionFromRegexFullMatch` to its own function as the
  logic is reused.
- Prefer `find` prefix on functions that may return `undefined` and
  `get` prefix for those that always return a value.

tests/integration/presentation/electron/preload/WindowVariablesProvider.spec.ts

@@ -23,7 +23,7 @@ function checkAllowedType(value: unknown) {
   if (Array.isArray(value)) {
     return value.every(checkAllowedType);
   }
-  if (type === 'object' && value !== null) {
+  if (type === 'object' && value !== null && value !== undefined) {
     return (
       // Every key should be a string
       Object.keys(value).every((key) => typeof key === 'string')