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/unit/presentation/components/Scripts/View/Tree/TreeViewAdapter/UseTreeViewNodeInput.spec.ts

@@ -92,7 +92,7 @@ function mountWrapperComponent(categoryIdRef: Ref<number | undefined>) {
   const useStateStub = new UseCollectionStateStub();
   const parserMock = mockCategoryNodeParser();
   const converterMock = mockConverter();
-  let returnObject: ReturnType<typeof useTreeViewNodeInput>;
+  let returnObject: ReturnType<typeof useTreeViewNodeInput> | undefined;
 
   shallowMount({
     setup() {
@@ -107,6 +107,10 @@ function mountWrapperComponent(categoryIdRef: Ref<number | undefined>) {
     },
   });
 
+  if (!returnObject) {
+    throw new Error('missing hook result');
+  }
+
   return {
     returnObject,
     useStateStub,