ERROR IN LINE 4

I think you're actually doing it correctly, it's just that the browser is giving you more feedback than what is shown in the video (which is using an older browser version). When I run your code, the console also shows me which line of code is having the issue. Based on the sequence of your console.log statements, the browser SHOULD throw an uncaught error on that first call to the function since it uses 'nine'. When I move your console.log statements around so that it runs the function with a few valid numbers first, the console spits out the random numbers and then once it gets to one of the console.log statements with the invalid numbers, it throws the uncaught error.

In other words, looks good to me! :)

Dave is correct, nothing wrong actually :-) the first call getRandomNumber('nine', 24) falls into that nice condition, and throw new Error("ERROR") is invoked, therefore we see that Uncaught Error: ERROR ... in console. Like this (it actually halts at first console.log already, the next console.log won't be invoked as you can see)

function getRandomNumber( lower, upper ) {
  if (isNaN(upper) || isNaN(lower)) {
    throw new Error("ERROR"); 
  } 
  return Math.floor(Math.random() * (upper - lower + 1)) + lower;
}

console.log( 
  getRandomNumber( 'nine', 24 ) // isNaN('nine') === true => throw ERROR in getRandomNumber()
); 

console.log( 
  getRandomNumber( 1, 100 ) // lower (1) and upper (100) are not NaN, no error
); 

console.log( 
  getRandomNumber( 200, 'five hundred' ) // isNaN('five hundred') === true => throw ERROR in getRandomNumber()
); 

console.log(
  getRandomNumber( 1000, 20000 ) // lower (1000) and upper (20000) are not NaN, no error
); 

console.log(
  getRandomNumber( 50, 100 ) // lower (50) and upper (100) are not NaN, no error
); 

Thank you guys!!! thanks for the feedback... we keep going!