Change background-color cells with ids via Javascript

Question

Guys I’m not able to change the background-color of my cells through their ids using Javascript. Gives the following error: Uncaught Typeerror: Cannot read Property 'style' of null.

Does anyone know how to solve? Follows below my code:

function criarTabela(){
    // vamos criar o elemento HTML table
    var tabela = document.createElement("table");
    tabela.border = "1px";
    tabela.cellSpacing = "0px";
    tabela.cellPadding = "3px";
 
    // vamos criar o corpo da tabela, ou seja, o tbody 
    var corpo = document.createElement("tbody");
    tabela.appendChild(corpo);
     
    // vamos criar três linhas contendo quatro células cada uma
    for(var i = 0; i < 151; i++){
      var linha = corpo.insertRow(-1);
       
      for(var j = 0; j < 5; j++){
         var celula = linha.insertCell(-1);
         
         celula.setAttribute("id", "lin"+i+"col"+j);
      }
    }
 
    // vamos anexar a tabela recém-criada a um elemento div
    var container = document.getElementById("container");
    container.appendChild(tabela);
  }  

cria.addEventListener('click', criarTabela);

let lin1col0 = document.getElementById('lin1col0');
let lin2col0 = document.getElementById('lin2col0');
let lin3col0 = document.getElementById('lin3col0');
let lin4col0 = document.getElementById('lin4col0');
let lin5col0 = document.getElementById('lin5col0');

let num = 1;

switch(num){
  case 1:
  lin1col0.style.backgroundColor = "red";
  break;
  case 2:
  lin2col0.style.backgroundColor ="red";
  break;
  case 3:
  lin3col0.style.backgroundColor = "red";
  break;
  case 4:
  lin4col0.style.backgroundColor = "red";
  break;
  case 5:
  lin5col0.style.backgroundColor = "red";
  break;
  default:
  alert("Erro!");
}
}

It helps to put the rest of the code. See above.