Inconsistent map behaviour

[dan1elhughes]

👋 When using a map that contains a newly defined type, like this:

type Foo uint

type Bar struct {
	Foo        Foo            `json:"foo"`
	FooInKey   map[Foo]bool   `json:"fooInKey"`
	FooInValue map[string]Foo `json:"fooInValue"`
}

the key value in the map does not become number as expected. The output instead:

export class Bar {
    foo: number;
    fooInKey: {[key: Foo]: boolean};
//                   ^ here
    fooInValue: {[key: string]: number};
}

I have created a PR to demonstrate the behaviour here.

Thanks!