Assigning to a string fails if it was previously compared to an enum

TypeScript Version: What is installed on the TypeScript playground

Assigning to a string fails if it was previously compared to an enum

If you run the code below in the TypeScript playground, line widgetName += 'AddSomething' errors out with Type 'string' cannot be assigned to type 'Widgets'.

However, if I cast the enum on the previous line to string (widgetName == <string> Widgets.ComparableHomeSales), everything compiles fine.

In addition, if I replace widgetName += 'AddSomething'; with widgetName = widgetName + 'AddSomething';, it also compiles fine.

Code

enum Widgets {
    ComparableHomeSales = 'ComparableHomeSales',
    PriceHistory = 'PriceHistory'
}

class WidgetDescription {
    private name: Widgets;

    constructor(name: Widgets) {
        this.name = name;
    }

    get Name(): Widgets {
        return this.name;
    }
}

// code implementation
let widgetDescription: WidgetDescription = new WidgetDescription(Widgets.ComparableHomeSales);
let widgetName: string = widgetDescription.Name;

if (widgetName == Widgets.ComparableHomeSales) {
    widgetName += 'AddSomething'; // <-- ERROR
}

Expected behavior:

widgetName += 'AddSomething'; should work

Actual behavior:

widgetName += 'AddSomething'; does not work

Playground Link:
Link