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/application/Parser/DocumentationParser.ts

@@ -1,9 +1,6 @@
 import type { DocumentableData, DocumentationData } from '@/application/collections/';
 
 export function parseDocs(documentable: DocumentableData): readonly string[] {
-  if (!documentable) {
-    throw new Error('missing documentable');
-  }
   const { docs } = documentable;
   if (!docs) {
     return [];