Unable to create a 2d array

I have a class called Pixel and I want to create an array holding arrays of Pixel-objects
I tried tons of stuff but I can’t get it to work. I just get the error that Pixel[][] is not assignable to type number[]
This is how I instantiate it: let cols: Pixel[][] = []

Welcome, @jkohlin!

In an empty JavaScript project, this seems to work for me just fine:

class Pixel {
let cols: Pixel[][] = []

Do you perhaps have a previous definition for cols somewhere in your code?