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/TheScriptsView.vue

@@ -71,6 +71,9 @@ export default defineComponent({
     const searchHasMatches = ref(false);
     const trimmedSearchQuery = computed(() => {
       const query = searchQuery.value;
+      if (!query) {
+        return '';
+      }
       const threshold = 30;
       if (query.length <= threshold - 3) {
         return query;
@@ -94,7 +97,7 @@ export default defineComponent({
 
     function updateFromInitialFilter(filter?: IFilterResult) {
       searchQuery.value = filter?.query;
-      searchHasMatches.value = filter?.hasAnyMatches();
+      searchHasMatches.value = filter?.hasAnyMatches() ?? false;
     }
 
     function subscribeToFilterChanges(filter: IReadOnlyUserFilter) {