Hey Egor,

I think this issue might be coming because of null pointer exception.

Try changing this below code block 

if(pageSize.size() > 0){
			limitSize = pageSize[0].Number_Records__c.intValue() ;
		}

to

if(pageSize.size() > 0 && pageSize[0].Number_Records__c != null){
			limitSize = pageSize[0].Number_Records__c.intValue() ;
		}

Your Final output will be like this. Please use below code

public class ParseCSVController {
    public Blob csvFileBody		{get;set;}
	public String csvAsString		{get;set;}
	public String[]csvFileLines	{get;set;}
	public List<Car_detail__c> detailList		{get;set;}
    public List<Car_Detail__c> showNow			{get;set;}
	public List<NumRecOnPage__c>	pageSize		{get;set;} 
    public Map<String,Integer>mapOfFields		{get;set;}
	public Integer resultSize {get;set;} 
	public Integer pageNumber {get;set;} 
    public Integer limitSize {get;set;}
    public Integer counter= 0;
	
	public ParseCSVController(){
        csvFileLines 	= new String[]{};
        showNow= new List<Car_Detail__c>();
        detailList= new List<Car_detail__c>();
        mapOfFields		= new Map<String,Integer>();       
        pageSize= NumRecOnPage__c.getAll().values();
		limitSize = 0;
		if(pageSize.size() > 0 && pageSize[0].Number_Records__c != null){
			limitSize = pageSize[0].Number_Records__c.intValue() ;
		}
        resultSize= 0;
        pageNumber= counter; 
	}
       
    public Boolean getHasNext(){
        if(pageNumber < getNumPages()){
            return true;
        }
        return false;
    }
    
	public boolean getHasPrevious(){
        if(pageNumber>1){
			return true;
        }
		return false;
    }
    
    public void Next(){
        showNow.clear();
        counter+=1;
        pageNumber += 1;      
        integer i0 = counter * limitSize;
        for(integer i = i0 ;i<resultSize;i++){
            if(i<(i0+limitSize)){
                showNow.add(detailList.get(i));
                }else break;
            }
    }
    
	public void Previous(){
        showNow.clear();
        pageNumber = pageNumber-1;
        counter=counter-1;       
        integer i0 = counter * limitSize;      
        for(integer i = i0; i < resultSize; i++){
            if(i < (i0+limitSize)){
                showNow.add(detailList.get(i));
            }else break;
        }
	}
        
	public void Reload(){
        showNow.clear();
        pageNumber = 1;
        counter = 0;
        integer i0 = counter * limitSize;
        for(integer i=i0;i<resultSize;i++){
            if(i<i0+limitSize){
                showNow.add(detailList.get(i));
                }else break;
            }  
	}
    
	public integer getNumPages(){
        integer ost = math.mod(resultSize, limitSize);
        if(ost>0){
        	return resultSize/limitSize+1;
        }
        return resultSize/limitSize;
	}
    
    public void First(){
        counter = 0;
        pageNumber = 1;
        showNow.clear();
        for(integer i=0;i<resultSize;i++){
                if(i<limitSize){
                	showNow.add(detailList.get(i));
                }else break;
		}  
	}
    
	public void Last(){
        counter = getNumPages()-1;
        pageNumber = getNumPages();
        showNow.clear();        
        integer i0 = counter*limitSize;
		for(integer i=i0;i<resultSize;i++){
                if(i<(i0+limitSize)){
                showNow.add(detailList.get(i));
                }else break;
		}  
	}
    
    public integer getCounterValue(){
		return counter;
	}
}