fix migration crash

Author: parveshneedhoo

src/ios/FileUploader.h

@@ -1,6 +1,7 @@
 #import <Foundation/Foundation.h>
 #import "UploadEvent.h"
 #import <AFNetworking/AFNetworking.h>
+#import <math.h>
 NS_ASSUME_NONNULL_BEGIN
 @protocol FileUploaderDelegate <NSObject>
 @optional

src/ios/FileUploader.m

@@ -36,14 +36,25 @@ -(id)init{
             NSData* serverData = weakSelf.responsesData[@(task.taskIdentifier)];
             NSString* serverResponse = serverData ? [[NSString alloc] initWithData:serverData encoding:NSUTF8StringEncoding] : @"";
             [weakSelf.responsesData removeObjectForKey:@(task.taskIdentifier)];
-            [weakSelf saveAndSendEvent:@{
-                @"id" : uploadId,
-                @"state" : @"UPLOADED",
-                @"statusCode" : @(((NSHTTPURLResponse *)task.response).statusCode),
-                @"serverResponse" : serverResponse,
-                @"uploadDuration" : @(duration)
-            }];
+            if (isnumber(duration)) {
+                [weakSelf saveAndSendEvent:@{
+                    @"id" : uploadId,
+                    @"state" : @"UPLOADED",
+                    @"statusCode" : @(((NSHTTPURLResponse *)task.response).statusCode),
+                    @"serverResponse" : serverResponse,
+                    @"uploadDuration" : @(duration)
+                }];
+            } else {
+                [weakSelf saveAndSendEvent:@{
+                    @"id" : uploadId,
+                    @"state" : @"UPLOADED",
+                    @"statusCode" : @(((NSHTTPURLResponse *)task.response).statusCode),
+                    @"serverResponse" : serverResponse,
+                    @"uploadDuration" : @"N/A"
+                }];
+            }
         } else {
+            [weakSelf.responsesData removeObjectForKey:@(task.taskIdentifier)];
             [weakSelf saveAndSendEvent:@{
                 @"id" : uploadId,
                 @"state" : @"FAILED",