More Complex Aliased Conditions

AliasedCondition.ts

const isDog = animal.kind === 'Dog';
const isCat = animal.kind === 'Cat';
const canSpeak = isDog || isCat; // Also retains CFA information

if (!canSpeak) {
    throw new Error('What does the Fox say?');
}

return isCat 
           ? animal.purr() 
           : animal.bark(); // Without the throw above this would be `Fox | Dog`