@reflectErr static struct E {}

static assert(is(Err!string == Err!string));
static assert(is(Err!(Err!string) == Err!string));
static assert(is(Err!E == E));
static assert(is(Err!Exception == Exception));

static assert(is(typeof("str".err) == Err!string));
static assert(is(typeof(E().err) == E));
static assert(is(typeof(new Exception("str").err) == Exception));