ERROR: Attempt to de-reference a null object
Error is in expression '{!save}' in component <apex:commandButton> in page installer_view


My Visualforce page:
<apex:page standardController="Installers__c" showHeader="true" tabStyle="Installers__c" extensions="MultiAttachmentController">
<apex:sectionHeader subtitle="{!Installers__c.Name}" title="Installer"/>
<chatter:feedWithFollowers entityId="{!Installers__c.id}"/>
<br>
</br>
<apex:form >
<apex:actionRegion >
<apex:pageblock title="Installer Detail" mode="mainDetail">
<apex:pageBlockButtons >
<apex:commandButton value="Edit" action="{!Edit}" style="display: inline;"  />
<apex:commandButton value="Delete" action="{!Delete}"  />
<apex:commandButton action="{!URLFOR($Action.Installers__c.Upload_Documents,Installers__c.Id)}" value="Upload Documents"/>
<apex:commandButton Action="{!save}" id="saveButton" value="Save" />
<apex:commandButton Action="{!Cancel}" id="cancelButton" value="Cancel" style="display: None;" />
........

My Component
<apex:component controller="MultiAttachmentController" allowDML="true">
    <apex:attribute name="objId" type="String" description="The id of the object to manage attachments for" required="true" assignTo="{!sobjId}"/>
    <apex:form id="attForm">
        <apex:pageBlock title="Upload Attachments">
            <apex:repeat value="{!newAttachments}" var="newAtt">
                <apex:pageBlockSection columns="3">
                  <apex:outputLabel value="Title">            
                  <apex:selectList id="Title" value="{!Title}" size="1">
.......................

My Controller
public with sharing class MultiAttachmentController
{

    public String delet { get; set; }
  
    id token = ApexPages.currentPage().getParameters().get('_CONFIRMATIONTOKEN');
    Id attId = System.currentPageReference().getParameters().get('id');
  
    public MultiAttachmentController(ApexPages.StandardController stdcontroller2) {

    }

    // the parent object it
    public Id sobjId {get; set;}
  
    // list of existing attachments - populated on demand
    public List<Attachment> attachments ;
    public List<Note> Notes ;
  
    //list of picklist values
       public String Title {get; set;}
       
         
    // list of new attachments to add
    public List<Attachment> newAttachments {get; set;}
  
    // the number of new attachments to add to the list when the user clicks 'Add More'
    public static final Integer NUM_ATTACHMENTS_TO_ADD=5;

    // constructor
    public MultiAttachmentController()
    {
        // instantiate the list with a single attachment
        newAttachments=new List<Attachment>{new Attachment()};
    }
....................

I get this error in only View mode(Inline Editing). When i am in Edit mode i dont get this error.