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/Script/CategoryCollectionParseContext.ts

@@ -17,8 +17,7 @@ export class CategoryCollectionParseContext implements ICategoryCollectionParseC
     scripting: IScriptingDefinition,
     syntaxFactory: ISyntaxFactory = new SyntaxFactory(),
   ) {
-    if (!scripting) { throw new Error('missing scripting'); }
     this.syntax = syntaxFactory.create(scripting.language);
-    this.compiler = new ScriptCompiler(functionsData, this.syntax);
+    this.compiler = new ScriptCompiler(functionsData ?? [], this.syntax);
   }
 }