Test added typed exception

Also, now that I've found "todo", use it to skip the two known failing tests

t/sum.t

@@ -3,12 +3,13 @@ BEGIN { @*INC.unshift: './lib'; }
 
 use Test;
 
-plan 62;
+plan 63;
 
 use Sum;
 ok(1,'We use Sum and we are still alive');
 lives_ok { X::Sum::Final.new() }, 'X::Sum::Final is available';
 lives_ok { X::Sum::Missing.new() }, 'X::Sum::Missing is available';
+lives_ok { X::Sum::Spill.new() }, 'X::Sum::Spill is available';
 lives_ok { X::Sum::Push::Usage.new() }, 'X::Sum::Push::Usage is available';
 lives_ok { eval 'class foo1 does Sum { method finalize { }; method add { }; method push { }; }' }, 'Sum composes when interface is implemented';
 dies_ok { eval 'class fooX does Sum { }' }, 'Sum requires interface to compose';
@@ -19,9 +20,8 @@ lives_ok { eval 'class foo5 does Sum does Sum::Marshal::BufValues { method final
 lives_ok { eval 'class foo6 does Sum does Sum::Marshal::Pack[] { method finalize { }; method add { }; }' }, 'Sum::Marshal::Pack composes and provides push';
 lives_ok { eval 'class foo7 does Sum::Marshal::Pack::Bits[ :accept(Int) ] { method finalize { }; method add { }; }' }, 'Sum::Marshal::Pack::Bits composes';
 
-#?rakudo skip 'shared crony composition'
+todo "Waiting on resolution for diamond composition RT.",2;
 lives_ok { eval 'class fooC1 does Sum does Sum does Sum::Marshal::StrOrds does Sum::Marshal::BufValues { method finalize { }; method add { }; }' }, 'Two Sum::Marshal subroles can compose with same crony';
-#?rakudo skip 'shared crony composition'
 lives_ok { eval 'class fooC2 does Sum does Sum does Sum::Marshal::Pack::Bits[ ] does Sum::Marshal::Pack::Bits[ :accept(Int) ] { method finalize { }; method add { }; }' }, 'Two Sum::Marshal::Pack subroles can compose with same crony';
 
 lives_ok {