Refactor response mappers to standardize currentUserId type handling

This commit updates the response mappers in the articles and comments modules by changing the type of `currentUserId` from `string | null` to `string`. This change enhances code consistency and clarity across the mappers, ensuring a more uniform handling of user ID values.

Author: yamcodes

src/articles/mappers/to-articles-response.ts

@@ -8,7 +8,7 @@ import type { ArticlesResponse, EnrichedArticle } from "../interfaces";
  */
 export function toArticlesResponse(
 	enrichedArticles: EnrichedArticle[],
-	{ currentUserId }: { currentUserId?: string | null } = {},
+	{ currentUserId }: { currentUserId?: string } = {},
 ): ArticlesResponse {
 	const myArticles = enrichedArticles.map((article) => {
 		const myFavorites =

src/articles/mappers/to-response.ts

@@ -5,7 +5,7 @@ type ToResponseParams = {
 	 * The ID of the current user
 	 * If provided, the article will be enriched with the current user's information, including article favorites and author following
 	 */
-	currentUserId?: string | null;
+	currentUserId?: string;
 };
 
 /**

src/comments/mappers/to-response.mapper.ts

@@ -9,7 +9,7 @@ import type { EnrichedComment } from "../interfaces";
  */
 export function toCommentResponse(
 	enrichedComment: EnrichedComment,
-	{ currentUserId }: { currentUserId?: string | null } = {},
+	{ currentUserId }: { currentUserId?: string } = {},
 ): {
 	comment: {
 		id: string;
@@ -53,7 +53,7 @@ export function toCommentResponse(
  */
 export function toCommentsResponse(
 	enrichedComments: EnrichedComment[],
-	{ currentUserId }: { currentUserId?: string | null } = {},
+	{ currentUserId }: { currentUserId?: string } = {},
 ): {
 	comments: Array<{
 		id: string;