Help I don't know what I'm doing wrong :(

I’m doing the rock, paper, scissors task and I’ve typed it all up but when I try to call my function I get an error saying its not a function. please help me.

const getUserChoice = (userInput) => {
  userInput = userInput.toLowerCase();
  if (userInput === 'rock' || userInput === 'paper' || userInput === 'scissors') { 
    return userInput;
  } else {
    console.log('ERROR. Please input rock, paper, or scissors.')

This is what I typed up.

.toLowerCase() is a string method, can only be called on strings. Calling this method on an integer (4) will result in an error

Thank you so much. It’s working now. Can’t believe I didn’t notice that