Getting an error saying matrix is undefined when I already initialized it [closed]

Getting an error saying

this.boardMatrix[i][j] = 1;
                       ^
TypeError: Cannot set properties of undefined (setting '2')

When I already have a private method that initializes the matrix to zeros when the constructor is called. This is a simplified version of the class:

class gameBoard {
constructor() {
    this.boardMatrix = this.#_initializeBoard;
  }
#_initializeBoard() {
    let board = [];
    for (let i = 0; i < 10; i++) {
      board.push([0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
    }
    return board;
  }
  placeShip(i, j, axis) {
      // some code
      this.boardMatrix[i][j] = 1;
  }
}

And here’s how I triggered the error:

console.log(gameboard.boardMatrix());