TypeError: exports.[interface_name] is not a constructor

I’ve created an Interface in Typescript NodeJS but I cannot wrap my head-around the error that says:

TypeError: exports.Something is not a constructor

interface Something {
    name: string;
    message: string;
    stack?: string;
}

interface SomethingConstructor {
    new(message?: string): Something;
    (message?: string): Something;
    readonly prototype: Something;
}

export declare var Something: SomethingConstructor;

This is what I have created as an Interface. And using it like so.

import { Something } from './dummy;

testFunction();

function testFunction() {
    try {
        const something = new Something("Here is a message");
        console.log(something.message)
    } catch (e) {
        console.log('in catch block');
        console.log(e);
    }

}

I expected this would run and prints “Here is a message” in the console but throws the “is not a constructor” error. I might not know how I should use interfaces. Please shed light on how can I do something like it?