type DooDad = 'SOMETHING' | 'ELSE' ;

class Interesting {

	public compiles = () : Promise<DooDad> => {
		return Promise.resolve().then(() => {
			if (1 < 2) {
				return 'SOMETHING';
			}
			return 'ELSE';
		});
	};

	public doesnt = () : Promise<DooDad> => {
		// TS2322: Type Promise<string> is not assignable to type Promise<DooDad>
		// Type 'string' is not assignable to type 'DooDad'
		return Promise.resolve().then(() => {
		//return Promise.resolve().then(() : DooDad => { // specifying return type here fixes the issue
			return 'ELSE';
		});
	};

	public slightlyDifferentErrorMessage = () : Promise<DooDad> => {
		// TS2322: Type Promise<string> is not assignable to type Promise<DooDad>
		return Promise.resolve().then(() => {
		//return Promise.resolve().then(() : DooDad => { // specifying return type here fixes the issue
			if (1 < 2) {
				return 'SOMETHING';
			}
			return 'SOMETHING';
		});
	};

}