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.

src/presentation/components/Scripts/View/Tree/ScriptsTree.vue

@@ -30,7 +30,7 @@ import { useSelectedScriptNodeIds } from './TreeViewAdapter/UseSelectedScriptNod
 export default defineComponent({
   props: {
     categoryId: {
-      type: [Number, undefined],
+      type: [Number],
       default: undefined,
     },
   },