[C#] Not all code paths return a value

Hey there,

So I'm working on some random dungeon-gen, and up until now it's being going great.

I am getting the error Not all code paths return a value I looked into the error, tweaked my code a little and I'm still not making any progress. Let me post my code.

 using UnityEngine;
 using System.Collections.Generic;
 
 public class DTileMap 
 {
     protected class DRoom 
     {
         public int left;
         public int top;
         public int width;
         public int height;
 
         public int right {
             get {return left + width - 1;}
         }
 
         public int bottom {
             get { return top + height - 1; }
         }
 
         public bool CollidesWith(DRoom other) {
             if( left > other.right-1 )
                 return false;
             
             if( top > other.bottom-1 )
                 return false;
             
             if( right < other.left+1 )
                 return false;
             
             if( bottom < other.top+1 )
                 return false;
             
             return true;
         }
 
     }
     
     int size_x;
     int size_y;
 
     int[,] map_data;
 
     List<DRoom> rooms;
 
     public DTileMap (int size_x, int size_y)
     {
         this.size_x = size_x;
         this.size_y = size_y;
 
         rooms = new List<DRoom> ();
 
         map_data = new int[size_x, size_y]; 
         for (int i=0; i < 30; i++) {
             int rsx = Random.Range (4,8);
             int rsy = Random.Range (4,8);
 
             DRoom r = new DRoom();
             r.left = Random.Range(0, size_x - rsx);
             r.top = Random.Range(0, size_y-rsy);
             r.width = rsx;
             r.height = rsy;
 
             if(!RoomCollides(r)){
                 rooms.Add (r);
                 MakeRoom(r);
             }
         }
     }
 
     bool RoomCollides(DRoom r)
     {
         foreach (DRoom r2 in rooms)
         {
             if(r.CollidesWith(r2))
             {
                 return true;
             }
         }
     }
 
     public int GetTileAt(int x, int y){
         return map_data [x, y];
     }
 
     void MakeRoom(DRoom r)
     {
         for (int x=0; x < r.width; x++)
         {
             for (int y=0; y < r.height; y++)
             {
                 if(x==0 || x == r.width -1 || y==0 || y==r.height -1)
                 {
                     map_data[r.left+x, r.top+y] = 3;
                 } 
                     else 
                 
                     {
                         map_data [r.left + x, r.top + y] = 1;
                     }
             }
         }
     }
 }
 
 // Id's
 // 0 = Void
 // 1 = Floor
 // 2 = Random
 // 3 = Wall

Now, the error code is pointing towards line 69, but I check all of my value on lines 21 - 34.

If you need any extra information, let me know. I've tried to figure this out, but I'm stumped...

Thanks in advance!