How to declare a 3D array and step through it?

I was working on this Leetcode problem Longest Line of Consecutive One in Matrix ^{subscription required}, but I cannot figure out why I get an error with regards to indexing. That is, Line 15: TypeError: Cannot set property '0' of undefined.

What's up with this bug?

/**
 * @param {number[][]} M
 * @return {number}
 */
var longestLine = function(M) {
  if(!M.length) return 0;

  let ones = 0;
  let dp = [[[]]];
  for(let i=0; i<M.length; i++){
    for(let j=0; j<M[0].length; j++){
      if(M[i][j] === 1){
        //dp[i][j] = undefined ? [] : dp[i][j];
        console.log(dp);
        dp[i][j][0] = i>0 ? dp[i-1][j][0] + 1 : 1;  // ----> line 15                        //left
        dp[i][j][1] = j>0 ? dp[i][j-1][1] + 1 : 1;                          //right
        dp[i][j][2] = (i > 0 && j > 0) ? dp[i-1][j-1][2]+1 : 1;             //upper left 
        dp[i][j][3] = (i > 0 && j < M.length - 1) ? dp[i-1][j+1][3] + 1 : 1; //lower left
        ones = Math.max(ones, dp[i][j][0], dp[i][j][1], dp[i][j][2], dp[i][j][3]); 
      }
    }
  }
  return ones;
};