why my iOS app is getting crashed on launching

i have built and run an iOS app and it crashed as soon as it got launched with this error in AppDelegate.swift:

Thread 1: Exception: "*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil

Following is the screenshot of code for reference.

i am not able to identify that error is present in which part of code so that i can debug it further by applying breakpoint.Need help in fixing this.

adding segment of code where objects are inserted into the array for reference.

+ (NSArray *)relevantURLSchemes {  NSMutableArray *result = [[NSMutableArray alloc] init];  for (NSBundle *bundle in [[self class] relevantBundles]) {    NSArray *urlTypes = [bundle objectForInfoDictionaryKey:@"CFBundleURLTypes"];    for (NSDictionary *urlType in urlTypes) {      [result addObjectsFromArray:urlType[@"CFBundleURLSchemes"]];    }  }  return result;}