From 58e637085d74ab17747d2dca0d8df93841ff29a2 Mon Sep 17 00:00:00 2001
From: MechaCat02 <fabian@diekaulbachs.de>
Date: Sun, 17 May 2026 18:30:39 +0200
Subject: [PATCH] bugfix: don't JSON.parse empty 200/201 bodies (0.19.1)
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$(addMangaToCollection crashed when the backend returned 201/200 with no body — the shared client only short-circuited 204. Now any empty body returns undefined.)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 backend/Cargo.lock                  |  2 +-
 backend/Cargo.toml                  |  2 +-
 frontend/package.json               |  2 +-
 frontend/src/lib/api/client.test.ts | 16 +++++++++++++++-
 frontend/src/lib/api/client.ts      | 10 +++++++++-
 5 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/backend/Cargo.lock b/backend/Cargo.lock
index d770042..503509c 100644
--- a/backend/Cargo.lock
+++ b/backend/Cargo.lock
@@ -1033,7 +1033,7 @@ checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
 
 [[package]]
 name = "mangalord"
-version = "0.19.0"
+version = "0.19.1"
 dependencies = [
  "anyhow",
  "argon2",
diff --git a/backend/Cargo.toml b/backend/Cargo.toml
index f9d9f6b..30fce3e 100644
--- a/backend/Cargo.toml
+++ b/backend/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.19.0"
+version = "0.19.1"
 edition = "2021"
 
 [lib]
diff --git a/frontend/package.json b/frontend/package.json
index f30a238..507f546 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.19.0",
+  "version": "0.19.1",
   "private": true,
   "type": "module",
   "scripts": {
diff --git a/frontend/src/lib/api/client.test.ts b/frontend/src/lib/api/client.test.ts
index f544715..49e292c 100644
--- a/frontend/src/lib/api/client.test.ts
+++ b/frontend/src/lib/api/client.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect, vi, beforeEach, afterEach, type MockInstance } from 'vitest';
-import { ApiError } from './client';
+import { ApiError, request } from './client';
 import { getManga } from './mangas';
 
 describe('request error envelope parsing', () => {
@@ -48,6 +48,20 @@ describe('request error envelope parsing', () => {
         expect(err.code).toBe('http_error');
     });
 
+    it('treats empty 200/201 bodies as undefined (no JSON.parse crash)', async () => {
+        // Regression: addMangaToCollection is typed `void` and the
+        // backend returns 201 (created) / 200 (already there) with
+        // no body. Without the empty-body short-circuit, `res.json()`
+        // would throw `JSON.parse: unexpected end of data`.
+        fetchSpy.mockResolvedValueOnce(new Response(null, { status: 201 }));
+        const created = await request<void>('/v1/whatever', { method: 'POST' });
+        expect(created).toBeUndefined();
+
+        fetchSpy.mockResolvedValueOnce(new Response(null, { status: 200 }));
+        const ok200 = await request<void>('/v1/whatever', { method: 'POST' });
+        expect(ok200).toBeUndefined();
+    });
+
     it('falls back to http_error code when JSON has no error envelope', async () => {
         fetchSpy.mockResolvedValueOnce(
             new Response(JSON.stringify({ message: 'oops' }), {
diff --git a/frontend/src/lib/api/client.ts b/frontend/src/lib/api/client.ts
index fc8db66..a272be7 100644
--- a/frontend/src/lib/api/client.ts
+++ b/frontend/src/lib/api/client.ts
@@ -56,10 +56,18 @@ export async function request<T>(path: string, init?: RequestInit): Promise<T> {
         }
         throw new ApiError(res.status, code, message);
     }
+    // Any empty body (not just 204) returns undefined — the manga-add
+    // endpoint, for instance, signals create-vs-already-present via
+    // 201/200 with no body, and callers typed `request<void>` would
+    // otherwise blow up on `res.json()` parsing an empty string.
     if (res.status === 204) {
         return undefined as T;
     }
-    return (await res.json()) as T;
+    const text = await res.text();
+    if (!text) {
+        return undefined as T;
+    }
+    return JSON.parse(text) as T;
 }
 
 export type Manga = {