Checking if an object in a 2D array is null triggers a null reference exception

I'm trying to access a point in a 2D array which has a chance of being null. I'm using if != null to make sure I don't trigger an error but that itself is triggering errors. Here's the code:

 public void Explode(int x, int y)
     {
         Debug.Log("Explode Function");
         bombWait = 0;
         Block b = rows[x].squares[y]; //Definitely not null so no need to check
         if (b != null)
         { 
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
   
         if (rows[x] != null)
             if (rows[x].squares[y + 1] != null) // Error usually called from this line but also from all the other if(rows[x + _] != null
                 b = rows[x].squares[y + 1];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
 
         if (rows[x + 1] != null)
             if (rows[x + 1].squares[y + 1] != null)
                 b = rows[x + 1].squares[y + 1];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
 
         if(rows[x + 1] != null)
             if (rows[x + 1].squares[y] != null)
                 b = rows[x + 1].squares[y];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
 
         if (rows[x + 1] != null)
             if (rows[x + 1].squares[y - 1] != null)
             b = rows[x + 1].squares[y - 1];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
         if (rows[x] != null)
             if (rows[x].squares[y - 1] != null)
         b = rows[x].squares[y - 1];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
 
         if (rows[x - 1] != null)
             if (rows[x - 1].squares[y - 1] != null)
             b = rows[x - 1].squares[y - 1];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
 
         if (rows[x - 1] != null)
             if (rows[x - 1] != null)
             b = rows[x - 1].squares[y];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
 
         if (rows[x - 1] != null)
             if (rows[x - 1].squares[y + 1] != null)
             b = rows[x - 1].squares[y + 1];
         if (b != null)
         {
             if (b.s != Block.Square.metal && b.s != Block.Square.empty)
             {
                 if (b.s == Block.Square.bomb)
                     b.bm.Die();
                 else
                     b.bm.ForceDie();
                 b.s = Block.Square.empty;
             }
         }
     }

Also I can't use try/catch because I'm trying to export for Webgl.