Why does this error appear in my C# code?

Index was outside the bounds of the array.

using  System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;


namespace CW2
{
    class LinkedNode
    {
        public char val;
        public LinkedNode next;
        public LinkedNode prev;
        public LinkedNode top;
        public LinkedNode bottom;



        //Default Constructor
        public LinkedNode()
        {
            val = ' ';
            next = null;
            prev = null;
            top = null;
            bottom = null;

        }
        //Constructor with parameter
        public LinkedNode(char value)
        {
            val = value;
            next = null;
            prev = null;
            top = null;
            bottom = null;
        }

        static void Main(string[] args)
        {

            //path to the file. 
            string path = @"C:\Users\Bradleigh\source\repos\MazeGame\\4-general-7x8.txt";
            string[] lines = System.IO.File.ReadAllLines(path);

            //First line holds row and column information
            string[] line = lines[0].Split(' ');
            int row = Convert.ToInt32(line[0]);
            int col = Convert.ToInt32(line[1]);
            //holding 0s 1s and starting point 's' and exit point 'o'
            char[,] maze_board = new char[row, col];

            for (int i = 1; i < lines.Length; i++)
            {
                //String to char array
                char[] arr = lines[i].ToCharArray();

                for (int j = 0; j < arr.Length; j++)
                    maze_board[i - 1, j] = arr[j];
            }
            //Display the maze now
            for (int i = 0; i < row; i++)
            {
                for (int j = 0; j < col; j++)
                    Console.Write(maze_board[i, j] + " ");
                Console.WriteLine();
                //Console.WriteLine();
            }

            //An array of nodes to create a four-way linked list for traversal of the maze
            LinkedNode[,] node = new LinkedNode[row, col];

            //Holds the start coords of the maze entrance
            int startX = -1, startY = -1;

            //Nested for loops that index and populate a 2d dimensional array which will be the maze
            for (int i = 0; i < lines.Length - 1; i++)
            {
                //Converts the maze file to an array of characters
                char[] arr = lines[i + 1].ToCharArray();
                for (int j = 0; j < arr.Length; j++)
                {
                    //Sets the array of nodes to be the number of tiles in the maze
                    node[i, j] = new LinkedNode(arr[j]);
                    //If the start of the maze is found, store the array coordinates
                    if (node[i, j].val == 's' || node[i, j].val == 'o')
                    {
                        startX = i;
                        startY = j;
                    }
                    //Checks that the left side of the maze tile is inside the array bounds
                    if (j - 1 >= 0)
                    {
                        //creates a link between the previous and next nodes
                        node[i, j].prev = node[i, j - 1];
                        node[i, j - 1].next = node[i, j];
                    }
                    //Does the same but with the top and bottom tiles
                    if (i - 1 >= 0)
                    {
                        node[i, j].top = node[i - 1, j];
                        node[i - 1, j].bottom = node[i, j];
                    }
                }
                Stack stack = new Stack();

                new Stack<linkednode>();
                //adds starting square to stack
                stack.Push(node[startX, startY]);
                //while the stack count is more than 0 pop current
                while (stack.Count > 0)
                {
                    var current = stack.Pop();
                    //marks visited with v 
                    node[startX, startY].val = 'v';
                    

                    //Queue q = new Queue();

                }
            }
        }
    }
}

Quote:

Please enter a maze file: 4x6-maze.txt

01010e
110101
011101
11s000

Press Enter to continue...

01010e
110101
011101
11sv00

Press Enter to continue...

01010e
110101
011101
11svv0

...

0101ve
1101v1
0111v1
11svvv

Press Enter to continue...
Goal reached...

The path is shown using ‘3’...

01013e
110131
011131
11s33v