fix: Returned error for 5xx server response has incorrect format (#2755)

Author: Moumouls

src/RESTController.ts

@@ -214,7 +214,8 @@ const RESTController = {
             promise.reject('Unable to connect to the Parse API');
           } else {
             // After the retry limit is reached, fail
-            promise.reject(response);
+            const error = await response.json();
+            promise.reject(error);
           }
         } else {
           promise.reject(response);

src/__tests__/RESTController-test.js

@@ -84,19 +84,21 @@ describe('RESTController', () => {
   });
 
   it('aborts after too many failures', async () => {
-    expect.assertions(1);
+    expect.assertions(3);
     mockFetch([
-      { status: 500 },
-      { status: 500 },
-      { status: 500 },
-      { status: 500 },
-      { status: 500 },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
       { status: 200, response: { success: true } },
     ]);
     try {
       await RESTController.ajax('POST', 'users', {});
     } catch (fetchError) {
       expect(fetchError).not.toBe(undefined);
+      expect(fetchError.code).toBe(1);
+      expect(fetchError.error).toBe('Internal server error.');
     }
   });
 
@@ -178,6 +180,23 @@ describe('RESTController', () => {
     }
   });
 
+  it('handles 5xx errors after retries', async () => {
+    expect.assertions(2);
+    mockFetch([
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+      { status: 500, response: { code: 1, error: 'Internal server error.' } },
+    ]);
+    try {
+      await RESTController.request('GET', 'classes/MyObject', {}, {});
+    } catch (error) {
+      expect(error.code).toBe(1);
+      expect(error.message).toBe('Internal server error.');
+    }
+  });
+
   it('handles X-Parse-Job-Status-Id header', async () => {
     mockFetch([{ status: 200, response: { results: [] } }], headers);
     const response = await RESTController.request(