Attach script twice.

I have implemented a simple 2d game in unityscript. I have a prefab with RigidBody2D,Circle Collider2D and a script attached to it[else doesnt perform simple lerp also]. In the scene I have created an empty game object and attached the same script and rigidbody2d. The script instantiates the prefab itself, which I attach in the inspector. Worked perfectly.

I am now translating the whole project into C#. But when I follow the similar steps as above, I get an error of UnassignedReferenceException and NullException. I know that it is caused because, I am not attaching anything to the script that I have attached to the prefab. But attaching anything to the prefab script causes more errors and seems wrong. Is there some fundamental rule that I have missed?

 using UnityEngine;
 using System.Collections;
 
 public class blobScript : MonoBehaviour {
 
     private sceneManagerScript scenemanager;
 
     public GameObject blobPrefab;         //Add from inspector.
     private GameObject blobobj;             //Instantiate the blob prefab to this object.
     public GameObject tutArrow;            //Tutorial arrow prefab.
 
 
     private GameObject[] tutobjs = new GameObject[3];
     private float[] tutPositions = new float[3]{3.1f,2.7f,2.3f};
 
     /*****Vectors*****/
     private Vector2 tempBlobScale;        //Tempvariable since blobobj's transform cannot be modified directly in C#.
     private Vector2 mouseDownPos;
     private Vector2 mouseUpPos;
     private Vector2 newPosition;
     private Vector2 v2delta;
     private Vector2 tempNewPosition;
 
     /*****INTEGERS*****/
     private static int SCORE;
     private static int LIVES;
 
     /*****Flags*****/
     private bool blobSet;
     private bool blobScaledUp;
     private bool CORRECT;
     private bool isCorrectWallSet;
     private bool diamondAnimation;
     private bool tutorialset;                  //Start the tutorial.
     private bool tutAnimating;                 //Start the animation.
     private bool[] animTutArrows= new bool[3]; //Used to animate the tutorial.
 
     private Color tempColor;
 
 
     //CORRECT MOVE OR NO
     public enum SWIPE {
         RIGHT,
         TOP,
         LEFT,
         BOTTOM
     }
     
     public SWIPE Swipe;
 
 
     void Start(){
         scenemanager=GameObject.Find("SceneManager").GetComponent<sceneManagerScript>();
         tempBlobScale=Vector2.zero;
         blobSet=false;
         blobScaledUp=false;
         CORRECT=false;
         tutorialset=false;
         SCORE=0;
 
         LIVES = PlayerPrefs.GetInt("LIVES");
     }
 
     void Update(){
         if(scenemanager.isState(sceneManagerScript.GAMESTATE.INITIALIZE)){
             if(!blobSet){initBlob();} //<<--UNASSIGNED REFERENCE ERROR    
             if(blobSet){scaleUpBlob();}
         }
 
         if(scenemanager.isState(sceneManagerScript.GAMESTATE.PLAY)){
             if(SCORE==0){
                 if(!tutorialset){
                     setTutorial();
                 }else{setTutorialAnim();}                                             //Start animating the tutorial.
             }
 
             newPosition=Vector2.zero;
 
             if (Input.GetMouseButtonDown (0)) {
                 Debug.Log("MOUSE DOWN!!");
                 mouseDownPos = Input.mousePosition;} //Save position when Screen Touched.
 
             if (Input.GetMouseButtonUp (0)) {
                 Debug.Log("MOUSE UP!!");
                 mouseUpPos = Input.mousePosition;                            // api call to give the last position// user touched/mouse down
 
                 v2delta = mouseUpPos - mouseDownPos;               // difference between them
                 
                 if (v2delta.normalized.x >= CONSTANTS._TOUCHTHRESHOLD) {                     
                     newPosition.x = CONSTANTS._DISTANCE; 
                     changeSwipeTo(SWIPE.RIGHT);
                     Debug.Log("Swipe is : "+Swipe);
                 } else if (v2delta.normalized.x <= CONSTANTS._TOUCHTHRESHOLD) {                    
                     newPosition.x = -(CONSTANTS._DISTANCE);  
                     changeSwipeTo(SWIPE.LEFT);    
                     Debug.Log("Swipe is : "+Swipe);
                 } else if (v2delta.normalized.y <= CONSTANTS._TOUCHTHRESHOLD) {                    
                     newPosition.y = -(CONSTANTS._DISTANCE); 
                     changeSwipeTo(SWIPE.BOTTOM);
                     Debug.Log("Swipe is : "+Swipe);
                 } else if (v2delta.normalized.y >= CONSTANTS._TOUCHTHRESHOLD) {                    
                     newPosition.y = CONSTANTS._DISTANCE;
                     changeSwipeTo(SWIPE.TOP);
                     Debug.Log("Swipe is : "+Swipe);
                 } 
             }
             if(newPosition!=Vector2.zero){
                 if(Swipe.ToString().Equals(scenemanager.getCorrectWall().ToString())){
                     
                     tempNewPosition=newPosition;
                                                                                     
                     scenemanager.changeStateToSwiped();
                     mouseUpPos = Vector3.zero;
                     v2delta = Vector2.zero;
                 }else if(LIVES > 0){
                     
                     scenemanager.changeStateToWrongmove();
                     
                 }
                 else{
                     
                     tempNewPosition=newPosition;
                                                                                                 scenemanager.changeStateToWrongmove();
                     mouseUpPos = Vector3.zero;
                     v2delta = Vector2.zero;
 
                 
                     
                 }
             }
         }
     }
 
     void FixedUpdate(){
         if(scenemanager.isState(sceneManagerScript.GAMESTATE.SWIPED)){
             blobobj.transform.position = Vector2.Lerp (blobobj.transform.position, tempNewPosition, Time.deltaTime*7); //<<--NULL REFERENCE ERROR    
         }
     }
 
     /*This function instantiates the blob after the play button is pressed*/
     private void initBlob(){
         int randomIndex = Random.Range(0,4);                                                //To pickup a random color from the currentArrayOfColor[] in scenemanager.
         blobobj=(GameObject)Instantiate(blobPrefab,Vector2.zero,Quaternion.identity);
         blobobj.name=CONSTANTS._BLOBNAME;
         blobobj.renderer.material.color =scenemanager.currentArrayOfColor[randomIndex];     //Set random color.
         blobobj.renderer.material.shader=CONSTANTS._SHADER;
         blobobj.transform.localScale= Vector2.zero;                                            //Set scale to 0 since we have to scale up the blob.
         blobSet=true;
     }
 
     /*This function scales up the blob after it has been instantiated*/
     private void scaleUpBlob(){
         if(tempBlobScale.x<1.0f){tempBlobScale=blobobj.transform.localScale;}
         if(tempBlobScale.y<1.0f){
             tempBlobScale.x+=CONSTANTS._SCALEUPFACTOR;
             tempBlobScale.y+=CONSTANTS._SCALEUPFACTOR;
             blobobj.transform.localScale=tempBlobScale;
         }else{
             tempBlobScale.x=1.0f;
             tempBlobScale.y=1.0f;
             blobobj.transform.localScale=tempBlobScale;
             blobScaledUp=true;
         }
     }
 
    
     public bool isBlobScaledUp(){return blobScaledUp;}
     public bool getCORRECT(){return CORRECT;}
     public int getGain(){
         //TODO
         return 1;
     }
     public Color getColor(){return blobobj.renderer.material.color; }
     public GameObject getBlobObj(){return blobobj;}
 
     //Setters
     public void setCORRECT(bool flag){CORRECT = flag;}
     
     public void changeSwipeTo(SWIPE s){Swipe=s;}
 }

Thanks.