Trigger code to make it so that a User can only create X number of cases per month

maxCases.cls

trigger MaxCases on Case (before insert) {
	Integer maxCases = null;
    CaseSettings__c settings = CaseSettings__c.getValues('default');
    
    if (settings != null) {
        maxCases = Integer.valueOf(settings.MaxCases__c);
    }
    
    if (maxCases != null) {
        Set<Id> userIds = new Set<Id>();
        Map<Id, Integer> caseCountMap = new Map<Id, Integer>();
        
        for (Case c: trigger.new) {
            userIds.add(c.OwnerId);
            caseCountMap.put(c.OwnerId, 0);
        }
        
        Map<Id, User> userMap = new Map<Id, User>([
            select Name
            from User
            where Id in :userIds
        ]);
        
        for (AggregateResult result: [
            select count(Id),
            	OwnerId
            from Case
            where CreatedDate = THIS_MONTH and
            	OwnerId in :userIds
            group by OwnerId
        ]) {
            caseCountMap.put((Id) result.get('OwnerId'), (Integer) result.get('expr0'));
        }
        
        for (Case c: trigger.new) {
            caseCountMap.put(c.OwnerId, caseCountMap.get(c.OwnerId) + 1);
            
            if (caseCountMap.get(c.OwnerId) > maxCases) {
                c.addError('Too many cases created this month for user ' + userMap.get(c.OwnerId).Name + '(' + c.OwnerId + '): ' + maxCases);
            }
        }
    }
}

Was it necessary to initiate caseCountMap on line 15 with value of 0 when you replace all of the values in caseCountMap on line 32 using the same set of UserID's?

This can be very simple by just one query:

trigger MaxCases on Case (before insert) {
    Integer maxCases = null;
    CaseSettings__c settings = CaseSettings__c.getValues('default');
    
    if (settings != null) {
        maxCases = Integer.valueOf(settings.MaxCases__c);
    }
    Map<Id,AggregateResult> caseCountMap = new Map<id,AggregateResult>([select count(Id), OwnerId Id, Owner.Name from Case where CreatedDate = THIS_MONTH group by OwnerId,Owner.Name having count(id) >: maxCases]);
    //{00Gg0000001aNhLEAU=AggregateResult:{expr0=7, Id=00Gg0000001aNhLEAU, Name=Test}}
    for (Case c: trigger.new) {
        AggregateResult ar = caseCountMap.get(c.OwnerId);
        if (ar != null) {
            c.addError('Too many cases created this month for user ' + ar.get('Name') + '(' + c.OwnerId + '): ' + maxCases);
        }
    }
}

Hi,

I just want to know what values you have given in default in custom settings?
CaseSettings__c settings = CaseSettings__c.getValues('default');
It shows null values for me.

Thanks