fix(network): Handle http response from the server correctly

If the server responds correctly but without a success code (200), it did not call the error
handler. This commit fixes this.

Author: Alexis Oyama

Example/Tests/Classes/EventDataManagerTest.m

@@ -200,6 +200,34 @@ - (void)test_request_synchronous
     [OHHTTPStubs removeAllStubs];
 }
 
+- (void)test_response_code
+{
+    [LeanplumHelper setup_method_swizzling];
+    [LeanplumHelper start_production_test];
+    [LPEventDataManager deleteEventsWithLimit:10000];
+    [LPNetworkEngine setupValidateOperation];
+    [Leanplum_Reachability online:YES];
+    
+    // Simulate error from http response code.
+    [OHHTTPStubs stubRequestsPassingTest:^BOOL(NSURLRequest *request) {
+        return [request.URL.host isEqualToString:API_HOST];;
+    } withStubResponse:^OHHTTPStubsResponse * _Nonnull(NSURLRequest * _Nonnull request) {
+        NSData *data = [@"Fail" dataUsingEncoding:NSUTF8StringEncoding];
+        return [OHHTTPStubsResponse responseWithData:data statusCode:500 headers:nil];
+    }];
+    
+    NSArray *events = [LPEventDataManager eventsWithLimit:10000];
+    XCTAssertTrue(events.count == 0);
+    
+    [[LeanplumRequest post:@"sample3" params:nil] sendNow:YES];
+    [NSThread sleepForTimeInterval:0.2];
+    events = [LPEventDataManager eventsWithLimit:10000];
+    XCTAssertTrue(events.count == 1);
+    
+    [LPEventDataManager deleteEventsWithLimit:10000];
+    [OHHTTPStubs removeAllStubs];
+}
+
 - (void)test_uuid
 {
     [LeanplumHelper setup_method_swizzling];

Leanplum-SDK/Classes/LPNetworkOperation.m

@@ -165,10 +165,18 @@ - (void)runSynchronously:(BOOL)synchronous
             if (synchronous) {
                 dispatch_semaphore_signal(sem);
             }
+            
+            // Handle unsuccessful http response code.
+            NSError *responseError = error;
+            if (!responseError && [self HTTPStatusCode] != 200) {
+                responseError = [NSError errorWithDomain:NSURLErrorDomain
+                                                    code:[self HTTPStatusCode]
+                                                userInfo:nil];
+            }
 
-            if (error) {
+            if (responseError) {
                 if (self.errorBlock) {
-                    self.errorBlock(self, error);
+                    self.errorBlock(self, responseError);
                 }
             } else {
                 if (self.responseBlock) {