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/Menu/TheOsChanger.vue

@@ -31,14 +31,14 @@ export default defineComponent({
     const { modifyCurrentContext, currentState } = injectKey((keys) => keys.useCollectionState);
     const { application } = injectKey((keys) => keys.useApplication);
 
-    const allOses = computed<ReadonlyArray<IOsViewModel>>(() => (
-      application.getSupportedOsList() ?? [])
-      .map((os) : IOsViewModel => (
-        {
+    const allOses = computed<ReadonlyArray<IOsViewModel>>(
+      () => application
+        .getSupportedOsList()
+        .map((os) : IOsViewModel => ({
           os,
           name: renderOsName(os),
-        }
-      )));
+        })),
+    );
 
     const currentOs = computed<OperatingSystem>(() => {
       return currentState.value.os;