Fix purging empty class (#4676)

* Fix purging empty class

* remove fit

spec/ParseAPI.spec.js

@@ -1493,6 +1493,11 @@ describe('miscellaneous', function() {
     });
   });
 
+  it('purge empty class', (done) => {
+    const testSchema = new Parse.Schema('UnknownClass');
+    testSchema.purge().then(done).catch(done.fail);
+  });
+
   it('should not update schema beforeSave #2672', (done) => {
     Parse.Cloud.beforeSave('MyObject', (request, response) => {
       if (request.object.get('secret')) {

src/Routers/PurgeRouter.js

@@ -17,6 +17,11 @@ export class PurgeRouter extends PromiseRouter {
           cacheAdapter.role.clear();
         }
         return {response: {}};
+      }).catch((error) => {
+        if (!error || (error && error.code === Parse.Error.OBJECT_NOT_FOUND)) {
+          return {response: {}};
+        }
+        throw error;
       });
   }