[REQUIRED] Step 1: Describe your environment

• Xcode version: 13.0
• Firebase SDK version:8.9.1
• Installation method: Swift Package Manager
• Firebase Component: Database
• Target platform(s): iOS

[REQUIRED] Step 2: Describe the problem

• It appeared when we started using the SDK as dependency of one of our SPM package, before, we were using cocoapods and it was fine.
• FirebaseDatabase entities get mapped when app is launched and it intermittently crashes in FUtilities.intForString

Steps to reproduce:

What happened? How can we make the problem occur?
This could be a description, log/console output, etc.

• Happens when we launch the app since we starting mapping entities immediately
• Attached (crashlog.txt) is the crash report

If you have a downloadable sample project that reproduces the bug you're reporting, you will
likely receive a faster response on your issue.

Relevant Code:

// TODO(you): code here to reproduce the problem
+ (NSNumber *)intForString:(NSString *)string {
    static NSCharacterSet *notDigits = nil;
    if (!notDigits) {
        notDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    }
    if ([string rangeOfCharacterFromSet:notDigits].length == 0) {
        NSInteger num;
        NSScanner *scanner = [NSScanner scannerWithString:string];
        if ([scanner scanInteger:&num]) {
            return [NSNumber numberWithInteger:num];
        }
    }
    return nil;
}

crashlog.txt