Extent is not a constructor

This error message typically means that you're trying to use the `new` keyword with a variable that is not a constructor function.

For example:

const extent = 42;
const myExtent = new extent(); // throws "Extent is not a constructor"

To fix this error, make sure that the variable you're trying to instantiate with `new` is actually a constructor function. If it's not, you'll need to refactor your code to use a different approach.