I'm trying to create a class in TypeScript, where I initialise a property / field in a class. But whenever I compile this to JS using tsc and try to initialise this class, I always get an error.

class Component {
    type_: string;

    constructor(type_: string) {
        this.type_ = type_;
    }

    getDefinition(): Object {
        return {
            type: this.type_
        };
    };
}

export { Component };

Error:

        this.type_ = type_;
                   ^

TypeError: Cannot set property 'type_' of undefined
    at Component (/Users/GitHub/ts-module/lib/components/base.js:6:20)
    at Object.<anonymous> (/Users/GitHub/ts-module/test.js:3:1)
    at Module._compile (internal/modules/cjs/loader.js:1200:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1220:10)
    at Module.load (internal/modules/cjs/loader.js:1049:32)
    at Function.Module._load (internal/modules/cjs/loader.js:937:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47

Offending code:

const base = require('./lib/components/base');
const { Component } = base;
Component("Section");

This is literally the most basic example from the TS docs so I cannot for the life of me figure what I'm doing wrong...