Attempt to de-reference a null object error when logged user is not System Administrator

Question

I am trying to get article owner name and i'm getting this error when i'm not logged in as System Administrator. I tried changing permissions but it seems like there is no solution but, running code as System Admin. Only problem is that runAs is only permitted in Tests methods. is there any workaround?

@AuraEnabled
public static String getCommunityFeedbackOnArticleApexController(String recordId, String description, String articleName, String articleUrl) {
    // if required fields are not null or empty string
    if(description == null || description.equals('') && recordId == null || recordId.equals('')){
        return 'false';
    }
        try{

            User current = [SELECT Id, Contact.Name, Contact.Account.Name, Contact.AccountId FROM User WHERE Id =: UserInfo.getUserId()];

            Id articleId = Id.valueOf(recordId.rightpad(15, '0'));
            // gets sobject type __ka or __kav
            Schema.SObjectType objectToQuery = articleId.getSObjectType();
            String strObjectToQuery = String.valueOf(objectToQuery);
            // dynamically querying __ka or __kav object
            String strQuery = 'SELECT Article_Owner__r.Name FROM ' + strObjectToQuery + ' WHERE Id = \'' + recordId + '\' LIMIT 1'; 
            List<sObject> sObjectReturned  = Database.query(strQuery);

            String articleOwnerName;
            if(!sObjectReturned.isEmpty()){

                    // THE LINE BELLOW IS PRODUCING ERROR

                articleOwnerName = (String) sObjectReturned[0].getSobject('Article_Owner__r').get('Name');

            }
            else{
                articleOwnerName = 'Unknown author';
            }

            Article_Feedback__c articleFeedback = new Article_Feedback__c(

                Contact_Name__c = current.Contact.Name,
                Account_Name__c = current.Contact.Account.Name,
                Feedback_description__c = description,
                Article_Name__c = articleName,
                Article_Owner__c = articleOwnerName,
                Link_To_Article__c = articleUrl
                );

            insert articleFeedback;
            return 'true';

        }catch(Exception e){
            return 'message = ' + e.getMessage() + ' cause = '+ e.getCause() + ' line = ' + e.getLineNumber();

        }
        return'false';
}

message = Attempt to de-reference a null object, cause = null, line = 28

Answer 1

Check the Field Article_Owner__c on every object you might be querying (not sure which ones it is, you just call them __ka or __kav. Here, enable Read Access for all the profiles.

This is most definitely an error that happens because only your System Administrator can see the field and when running as another user sObjectReturned[0].getSobject('Article_Owner__r') returns null and this is where the NullPointerException happens.

Answer 2

The problem was in OWD(Org wide defaults) where community user did not have permission to access User details. After changing permissions from private to public, the problem dissapeared.