Fix no response API calls (#969)

## Description

Fixes #968

This PR fixes cases where our APIs do not return a response.

## Documentation

Does this require changes to the WorkOS Docs? E.g. the [API
Reference](https://workos.com/docs/reference) or code snippets need
updates.

```
[ ] Yes
```

If yes, link a related docs PR and add a docs maintainer as a reviewer.
Their approval is required.

Author: benoitgrelard

src/common/utils/fetch-client.ts

@@ -8,10 +8,9 @@ export class FetchClient {
     options: { params?: Record<string, any>; headers?: HeadersInit },
   ) {
     const resourceURL = this.getResourceURL(path, options.params);
-    const response = await this.fetch(resourceURL, {
+    return await this.fetch(resourceURL, {
       headers: options.headers,
     });
-    return { data: await response.json() };
   }
 
   async post<Entity = any>(
@@ -20,12 +19,11 @@ export class FetchClient {
     options: { params?: Record<string, any>; headers?: HeadersInit },
   ) {
     const resourceURL = this.getResourceURL(path, options.params);
-    const response = await this.fetch(resourceURL, {
+    return await this.fetch(resourceURL, {
       method: 'POST',
       headers: { ...getContentTypeHeader(entity), ...options.headers },
       body: getBody(entity),
     });
-    return { data: await response.json() };
   }
 
   async put<Entity = any>(
@@ -34,20 +32,19 @@ export class FetchClient {
     options: { params?: Record<string, any>; headers?: HeadersInit },
   ) {
     const resourceURL = this.getResourceURL(path, options.params);
-    const response = await this.fetch(resourceURL, {
+    return await this.fetch(resourceURL, {
       method: 'PUT',
       headers: { ...getContentTypeHeader(entity), ...options.headers },
       body: getBody(entity),
     });
-    return { data: await response.json() };
   }
 
   async delete(
     path: string,
     options: { params?: Record<string, any>; headers?: HeadersInit },
   ) {
     const resourceURL = this.getResourceURL(path, options.params);
-    await this.fetch(resourceURL, {
+    return await this.fetch(resourceURL, {
       method: 'DELETE',
       headers: options.headers,
     });
@@ -85,7 +82,14 @@ export class FetchClient {
       });
     }
 
-    return response;
+    const contentType = response.headers.get('content-type');
+    const isJsonResponse = contentType?.includes('application/json');
+
+    if (isJsonResponse) {
+      return { data: await response.json() };
+    }
+
+    return { data: null };
   }
 }
 

src/common/utils/test-utils.ts

@@ -2,9 +2,13 @@ import fetch, { MockParams } from 'jest-fetch-mock';
 
 export function fetchOnce(
   response: any = {},
-  { status = 200, ...rest }: MockParams = {},
+  { status = 200, headers, ...rest }: MockParams = {},
 ) {
-  return fetch.once(JSON.stringify(response), { status, ...rest });
+  return fetch.once(JSON.stringify(response), {
+    status,
+    headers: { 'content-type': 'application/json;charset=UTF-8', ...headers },
+    ...rest,
+  });
 }
 
 export function fetchURL() {