Fixes issue where info logs would appear in error logs (#2647)

* Reproduction of #2639

* Make sure the error level options is enforced

spec/WinstonLoggerAdapter.spec.js

@@ -16,11 +16,19 @@ describe('info logs', () => {
         }, (results) => {
           if (results.length == 0) {
             fail('The adapter should return non-empty results');
-            done();
           } else {
             expect(results[0].message).toEqual('testing info logs');
-            done();
           }
+          // Check the error log
+          // Regression #2639
+          winstonLoggerAdapter.query({
+            from: new Date(Date.now() - 500),
+            size: 100,
+            level: 'error'
+          }, (results) => {
+            expect(results.length).toEqual(0);
+            done();
+          });
         });
       });
     });

src/Adapters/Logger/WinstonLogger.js

@@ -18,16 +18,15 @@ function updateTransports(options) {
       delete transports['parse-server-error'];
     } else if (!_.isUndefined(options.dirname)) {
       transports['parse-server'] = new (DailyRotateFile)(
-        Object.assign({
+        Object.assign({}, {
           filename: 'parse-server.info',
           name: 'parse-server',
         }, options));
       transports['parse-server-error'] = new (DailyRotateFile)(
-        Object.assign({
+        Object.assign({}, {
           filename: 'parse-server.err',
           name: 'parse-server-error',
-          level: 'error'
-        }, options));
+        }, options, { level: 'error'}));
     }
 
     transports.console = new (winston.transports.Console)(