Added missing application/json content-type when calling Shlink with payload

src/common/services/HttpClient.ts

@@ -1,10 +1,27 @@
 import { Fetch } from '../../utils/types';
 
+const applicationJsonHeader = { 'Content-Type': 'application/json' };
+const withJsonContentType = (options?: RequestInit): RequestInit | undefined => {
+  if (!options?.body) {
+    return options;
+  }
+
+  return options ? {
+    ...options,
+    headers: {
+      ...(options.headers ?? {}),
+      ...applicationJsonHeader,
+    },
+  } : {
+    headers: applicationJsonHeader,
+  };
+};
+
 export class HttpClient {
   constructor(private readonly fetch: Fetch) {}
 
   public readonly fetchJson = <T>(url: string, options?: RequestInit): Promise<T> =>
-    this.fetch(url, options).then(async (resp) => {
+    this.fetch(url, withJsonContentType(options)).then(async (resp) => {
       const json = await resp.json();
 
       if (!resp.ok) {
@@ -15,7 +32,7 @@ export class HttpClient {
     });
 
   public readonly fetchEmpty = (url: string, options?: RequestInit): Promise<void> =>
-    this.fetch(url, options).then(async (resp) => {
+    this.fetch(url, withJsonContentType(options)).then(async (resp) => {
       if (!resp.ok) {
         throw await resp.json();
       }