Vollständige Union-Behandlung mit Never-Typ-Zuweisung

type UserRole = "admin" | "editor" | "viewer";
 
function assertUnreachable(x: never): never {
  throw new Error(`Unexpected discriminant value: ${JSON.stringify(x)}`);
}
 
function getPermissions(role: UserRole): string[] {
  switch (role) {
    case "admin": return ["read", "write", "delete"];
    case "editor": return ["read", "write"];
    case "viewer": return ["read"];
    default: return assertUnreachable(role);
  }
}