Nil Block Checks (#394)

• In the OneSignalClient class that handles network request logic, there were rare cases where the SDK was attempting to execute blocks that could potentially be nil
• Adds checks to ensure these blocks aren't executed if they're nil (fixes #391)

iOS_SDK/OneSignalSDK/Source/OneSignalClient.m

@@ -108,7 +108,12 @@ - (void)executeSimultaneousRequests:(NSDictionary<NSString *, OneSignalRequest *
 - (void)executeRequest:(OneSignalRequest *)request onSuccess:(OSResultSuccessBlock)successBlock onFailure:(OSFailureBlock)failureBlock {
 
     if (request.method != GET && [OneSignal shouldLogMissingPrivacyConsentErrorWithMethodName:nil]) {
-        failureBlock([NSError errorWithDomain:@"OneSignal Error" code:0 userInfo:@{@"error" : [NSString stringWithFormat:@"Attempted to perform an HTTP request (%@) before the user provided privacy consent.", NSStringFromClass(request.class)]}]);
+        if (failureBlock) {
+            failureBlock([NSError errorWithDomain:@"OneSignal Error" code:0
+                    userInfo:@{@"error" : [NSString stringWithFormat:
+                                    @"Attempted to perform an HTTP request (%@) before the user provided privacy consent.", NSStringFromClass(request.class)]}]);
+        }
+
         return;
     }
 
@@ -156,7 +161,8 @@ - (void)handleMissingAppIdError:(OSFailureBlock)failureBlock withRequest:(OneSig
 
     [OneSignal onesignal_Log:ONE_S_LL_ERROR message:errorDescription];
 
-    failureBlock([NSError errorWithDomain:@"OneSignalError" code:-1 userInfo:@{@"error" : errorDescription}]);
+    if (failureBlock)
+        failureBlock([NSError errorWithDomain:@"OneSignalError" code:-1 userInfo:@{@"error" : errorDescription}]);
 }
 
 - (BOOL)validRequest:(OneSignalRequest *)request {